3.4 Inheritance

The inheritance of genes follows patterns.

Essential idea:

3.4 Inheritance

Understandings

Syllabus Reference

Applications and Skills

3.4 Inheritance

Syllabus Reference

https://quizlet.com/_90mr0b?x=1jqt&i=28b19k

3.4 Inheritance

Vocabulary

1. Genes are the sole determinants of traits (features)

2. Single genes code for most traits (features)

3. Dominant traits are the most common traits in a population

4. All mutations are harmful

5. Once a mutation is discovered, it can be “fixed”

6. Only certain people have “disease genes”

7. If a couple has a “one-in-four” risk of having a child with a disease, and their firstborn has the disease, the next three children will have a reduced risk.

8. Genetic diseases are always caused by recessive genes

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3.4 Inheritance

Inheritance Pretest - True or False?

PreTest

1. Where are genes found?
2. How do they control a characteristic?
3. When do we inherit them?
4. How do we predict inheritance?

3.4 Inheritance

A gene is a heritable factor that controls a specific characteristic

3.4.U1 ​Mendel discovered the principles of inheritance with experiments in which large numbers of pea plants were crossed.

• He developed the principles of inheritance by performing experiments on pea plants.
• Mendel discovered the principles of inheritance with experiments in which large numbers of pea plants were crossed

3.4 Inheritance

Gregor Mendel was an Austrian monk

3.4.U1 ​Mendel discovered the principles of inheritance with experiments in which large numbers of pea plants were crossed.

• Some characteristics cannot be inherited
• Mendel’s experiment used different types of pea plants, each of which reliably had the same characters when grown on its own
• Replicates and reliability in Mendel’s experiments
• Making quantitative measurements with replicates to ensure reliability: Mendel’s genetic crosses with pea plants generated numerical data
• Male and female parents contribute equally to offspring

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3.4 Inheritance

Gregor Mendel’s scientific experiments

3.4.U1 ​Mendel discovered the principles of inheritance with experiments in which large numbers of pea plants were crossed.

Chromosome

Genes

A body of condensed DNA containing many hundreds of genes

3.4 Inheritance

Chromosome:

3.4.U2 Gametes are haploid so contain only one allele of each gene.

Specific forms of the same gene.

Each allele has a different effect on the characteristic

3.4 Inheritance

Alleles:

3.4.U2 Gametes are haploid so contain only one allele of each gene.

The combination of alleles which an organism carries for a particular gene

Genotype: BB

Genotype: Bb

Genotype: bb

alleles

3.4 Inheritance

Genotype:

3.4.U2 Gametes are haploid so contain only one allele of each gene.

Principle of Dominance: Recessive alleles will be masked by dominant alleles

If an individual has two different alleles of a gene on a pair of chromosomes the individual is…

…homozygous

…heterozygous

If an individual has two copies of same allele of a gene on a pair of chromosomes the individual is…

The prefix homo- means…

‘same’

The prefix hetero- means…

‘other’

3.4 Inheritance

3.4.U3 The two alleles of each gene separate into different haploid daughter nuclei during meiosis.

An allele which is always expressed when it is present…

… in both homozygous and heterozygous genotypes.

Brown eye allele Blue eye allele

Brown eye phenotype

3.4 Inheritance

Dominant allele:

3.4.U5 Dominant alleles mask the effects of recessive alleles but co-dominant alleles have joint effects.

An allele which can only affect a phenotype when in a homozygous genotype

… it is only expressed when two recessive alleles are present.

Blue eye phenotype

Blue eye alleles

3.4 Inheritance

Recessive allele:

3.4.U5 Dominant alleles mask the effects of recessive alleles but co-dominant alleles have joint effects.

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the offspring of two plants or animals of different species or varieties

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an animal bred from parents of the same breed or variety.

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pollination of a flower or plant with pollen from another flower or plant

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The transfer of pollen from a male reproductive structure (an anther or male cone) to a female reproductive structure (a stigma or female cone) of the same plant or of the same flower.

Hybrid

Purebred

Cross pollination

Self-pollination

3.4 Inheritance

Define the following terms

3.4 U1 Mendel discovered the principles of inheritance with experiments in which large numbers of pea plants were crossed.

https://www2.palomar.edu/anthro/mendel/mendel_1.htm�

2. What were the two theories of inheritance popular before Mendel did his experiments. Explain what each of these theories proposed.

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1. "blending theory.“ - inherited traits blend from generation to generation
2. "pangenesis" - hereditary "particles" in our bodies are affected by the things we do during our lifetime.

3. Why did Mendel pick pea plants for his experiments?

• Can be grown easily in large numbers and their reproduction can be manipulated
• both male and female reproductive organs
• either self-pollinate themselves or cross-pollinate

3.4 Inheritance

Answer the following

3.4 U1 Mendel discovered the principles of inheritance with experiments in which large numbers of pea plants were crossed.

4. Describe Mendel’s two laws.

1. the principle of segregation
2. the principle of independent assortment

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Complete the quiz

https://www2.palomar.edu/anthro/practice/mendqui1.htm

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3.4 Inheritance

Answer the following

3.4 U1 Mendel discovered the principles of inheritance with experiments in which large numbers of pea plants were crossed.

Trait

• a distinguishing quality or characteristic, typically one belonging to a person.

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Pedigree

• the record of descent of an animal, showing it to be purebred.

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3.4 Inheritance

Define the following terms

3.4 U1 Mendel discovered the principles of inheritance with experiments in which large numbers of pea plants were crossed.

Each haploid sperm cell contains only one of the two alleles from the diploid parent cell

3.4 Inheritance

Sperm cells are produced by meiosis

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3.4.U4 Fusion of gametes results in diploid zygotes with two alleles of each gene that may be the same allele or different alleles.

Ova (egg cells) are also produced by meiosis

• Law of Segregation:When gametes form, alleles are separated so that each gamete carries only one allele for each gene
• Law of Independent Assortment: The segregation of alleles for one gene occurs independently to that of any other gene

3.4 Inheritance

Define the following terms

3.4 U1 Mendel discovered the principles of inheritance with experiments in which large numbers of pea plants were crossed.

3.4 Inheritance

3.4.U1 Mendel discovered the principles of inheritance with experiments in which large numbers of pea plants were crossed.

3.4 Inheritance

A little bit of history...

So what did we learn?

3.4 Inheritance

3.4.U1 Mendel discovered the principles of inheritance with experiments in which large numbers of pea plants were crossed.

3.4 Inheritance

3.4.U1 Mendel discovered the principles of inheritance with experiments in which large numbers of pea plants were crossed.

• Mendel performed experiments on a variety of different pea plants, crossing these varieties by using the male pollen from one variety and transferring it to the female part of another variety

3.4 Inheritance

What is codominance?

3.4.S2 Comparison of predicted and actual outcomes of genetic crosses using real data.

• Co-dominance occurs when pairs of alleles are both expressed equally in the phenotype of a heterozygous individual
• Heterozygotes therefore have an altered phenotype as the alleles are having a joint effect. Examples include cows, blood types and some flowers

A, B, AB and O

The four common blood groups of the human ABO blood group system are determined by three alleles:

I^A, I^B, i

(but, one individual can possess only two alleles)

I^A & I^B are co-dominant and i is recessive

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3.4 Inheritance

Humans have 4 blood group phenotypes:

3.4.A1 Inheritance of ABO blood groups.

3.4 Inheritance

Humans have 4 blood group phenotypes:

3.4.A1 Inheritance of ABO blood groups.

3.4 Inheritance

The ABO blood type classification system uses the presence or absence of certain antigen on red blood cells to categorize blood into four types.

3.4.A1 Inheritance of ABO blood groups.

1.Write down the genotypes of a person with type B blood.

2. The wife is heterozygous for blood group A, the husband has blood group O. Determine the probability of:

A child having blood group O

A child having blood group A

3.4 Inheritance

Humans have 4 blood group phenotypes:

3.4.A1 Inheritance of ABO blood groups.

3,358 genes with a phenotype-causing mutation (OMIM, March 19, 2015)

It is unlikely that one parent will have a mutation on a disease related gene, but the probability that both parents have a mutation on the same gene is very small.

For example: Phenylketonuria (PKU) is a rare metabolic disorder that can be destructive to the nervous system, causing intellectual disability. About 1 out of every 15,000 babies is born with PKU.

3.4 Inheritance

Genetic diseases are very rare

3.4.U8 Many genetic diseases have been identified in humans but most are very rare.

“According to the US Bureau of Labor Statistics, the graduate of today will change career four to six times in a lifetime. By one estimate, 65 per cent of the jobs that will be available upon college graduation for students now entering high school (that's eight years from now) do not yet exist. Consider the new interdisciplinary field of genetic counselling, which combines biological science with social work and ethics - it was ranked as one of the "top 10" career choices of 2010 because it offered far more openings than could be filled by qualified applicants.”

You are a genetic counselor. A couple walk into your clinic and are concerned about their pregnancy. They each have one parent who is affected by cystic fibrosis (CF) and one parent who has no family history. Explain CF and its inheritance to them. Deduce the chance of having a child with CF and how it can be tested and treated.

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Use the following tools in your explanations:

• Pedigree chart
• Punnett grid
• Diagrams

3.4 Inheritance

Career-related Case Study

3.4.U6 Many genetic diseases in humans are due to recessive alleles of autosomal genes, although some genetic diseases are due to dominant or co-dominant alleles.

• A mutation in the CFTR gene causes secretions (e.g. mucus, sweat and digestive juices) which are usually thin instead become thick.
• This gene is located on chromosome 7.
• The gene product is a chloride ion channel
• Instead of acting as a lubricant, the secretions block tubes, ducts and passageways, especially in the lungs and pancreas.
• Despite therapeutic care lung problems in most CF sufferers leads to a early death (life expectancy is between 35 and 50 years).

3.4 Inheritance

Cystic Fibrosis (CF)

3.4.U6 Many genetic diseases in humans are due to recessive alleles of autosomal genes, although some genetic diseases are due to dominant or co-dominant alleles. AND 3.4.A3 Inheritance of cystic fibrosis and Huntington’s disease.

3.4 Inheritance

Sickle Cell is another example of codominance.

3.4.U6 Many genetic diseases in humans are due to recessive alleles of autosomal genes, although some genetic diseases are due to dominant or co-dominant alleles.

Huntington's Disease (HD) is a brain disorder that affects a person's ability to think, talk, and move. HD is caused by a mutation in the HTT gene on chromosome 4. Gene product is huntington. Function still researched.

3.4 Inheritance

Huntington’s Disease

3.4.U6 Many genetic diseases in humans are due to recessive alleles of autosomal genes, although some genetic diseases are due to dominant or co-dominant alleles. AND 3.4.A3 Inheritance of cystic fibrosis and Huntington’s disease.

3.4 Inheritance

Huntington's Disease (HD) is a brain disorder that affects a person's ability to think, talk, and move. HD is caused by a mutation in a gene on chromosome 4.

3.4.U6 Many genetic diseases in humans are due to recessive alleles of autosomal genes, although some genetic diseases are due to dominant or co-dominant alleles.

How is sex determined?

Is the male gender at risk of extinction?

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3.4 Inheritance

Guiding Questions:

3.4.A2 Red-green colour blindness and hemophilia as examples of sex-linked inheritance.

Autosomes

3.4 Inheritance

Sex Chromosomes

3.4.A2 Red-green colour blindness and hemophilia as examples of sex-linked inheritance.

Because a woman only contributes an X chromosome

3.4 Inheritance

The man determine the sex of the baby...

3.4.A2 Red-green colour blindness and hemophilia as examples of sex-linked inheritance.

Why do men suffer from colour blindness, baldness, and haemophilia more often than women?

Is the X-chromosome or the y-chromosome responsible?

Are these traits caused by dominant genes on the Y chromosome, or recessive genes on the X chromosome?

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3.4 Inheritance

Guiding Questions

3.4.A2 Red-green colour blindness and hemophilia as examples of sex-linked inheritance.

3.4 Inheritance

Watch These

3.4.A2 Red-green colour blindness and hemophilia as examples of sex-linked inheritance.

Read the article and the links then choose one of the activities

3.4 Inheritance

Watch These

3.4.A2 Red-green colour blindness and hemophilia as examples of sex-linked inheritance.

3.4 Inheritance

What number do you see?

3.4.A2 Red-green colour blindness and hemophilia as examples of sex-linked inheritance.

Non-homologous region

Non-homologous region

Examples of sex-linked genetic disorders:

- haemophilia

- colour blindness

Alleles in this regions are expressed whether they are dominant or recessive, as there is no alternate allele carried on the Y chromosome.

Sex-linked traits are those which are carried on the X-chromosome in the non-homologous region.

3.4 Inheritance

The sex chromosomes are non-homologous. There are many genes on the X-chromosome which are not present on the Y-chromosome.

3.4.U7 Some genetic diseases are sex-linked. The pattern of inheritance is different with sex-linked genes due to their location on sex chromosomes.

3.4 Inheritance

What number do you see?

3.4.A2 Red-green colour blindness and hemophilia as examples of sex-linked inheritance.

5 = normal vision

2 = red/green colour blindness

• The red-green gene is carried at locus Xq28.
• This locus is in the non-homologous region, so there is no corresponding gene (or allele) on the Y chromosome.
• Normal vision is dominant over colour-blindness.

Key to alleles:

N = normal vision

n = red/green colour

blindness

X^N X^N

Xⁿ Xⁿ

X^N Xⁿ

X^N Y

Xⁿ Y

no allele carried, none written

Normal female

Normal male

Affected female

Affected male

Carrier female

Human females can be homozygous or heterozygous with respect to sex-linked genes. Heterozygous females are carriers.

3.4 Inheritance

How is colour-blindness inherited?

3.4.A2 Red-green colour blindness and hemophilia as examples of sex-linked inheritance.

• a. colour blindness caused by recessive allele / colour blindness is recessive;�b. gene located on X chromosome/sex-linked;�c. X^b is allele for colour blindness and X^B is allele for normal colour vision/dominant allele;�d. male has one X and one Y chromosome;�e. male has only one copy of gene(s) located on X chromosome;�f. X chromosome (in males) comes from female parent;�g. any male receiving allele from mother will express the trait;�h. X^bY is genotype for colour blind male;�i. many more males have colour blindness than females;�j. female will express colour blindness only if is homozygous recessive/X^b X^b;�k. heterozygous/X^B X^b female is a carrier;�l. colour blind female could be born to colour blind father and carrier mother;
• Marks may be earned for use of annotated diagram/Punnett square to show points given above.
• Accept use of letters other than B and b as long as capital letter is used for dominant and lower case letter for recessive alleles. For using other improper notation (not showing X or Y), award [0] for the first misuse and then apply ECF to additional notation as long as usage is consistent.
• (Plus up to [2] for quality)

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3.4 Inheritance

Explain the inheritance of colour blindness (8 marks).

3.4.A2 Red-green colour blindness and hemophilia as examples of sex-linked inheritance.

• Blood clotting is an example of a metabolic pathway – a series of enzyme-controlled biochemical reactions.
• It requires globular proteins called clotting factors.
• A recessive X-linked mutation in hemophiliacs results in one of these factors (Factor VIII) not being produced.
• Therefore, the clotting response to injury does not work and the patient can bleed to death.

3.4 Inheritance

Hemophilia

3.4.A2 Red-green colour blindness and hemophilia as examples of sex-linked inheritance.

Segregation refers to alleles of the same gene separating into different gametes (i.e. one sperm gets a "A" and the other a "a" from a heterozygous "Aa" male. This occurs during meiosis 1.

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Independent assortment is when different genes, located on different chromosomes move independently from each other (i.e. what happens to gene "A" has no effect on gene "B"). Occurs during metaphase 1 of meiosis.

10.2 Inheritance

Both independent assortment and segregation occur during meiosis

10.2.U1:  Unlinked genes segregate independently as a result of meiosis.  

Unlinked genes (traits are on different chromosomes).

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Monohybrid cross is when one gene is crossed.

10.2 Inheritance

10.2.U1:  Unlinked genes segregate independently as a result of meiosis.  

• Unlinked Genes(traits are on different chromosomes).

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• Dihybrid Cross (more than one gene across two chromosomes).

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• Eg Eye Colour and Hair Colour

10.2 Inheritance

10.2.U1:  Unlinked genes segregate independently as a result of meiosis.  

10.2 Inheritance

10.2.U1:  Unlinked genes segregate independently as a result of meiosis.  

• Linked genes will tend to be inherited together and hence don’t follow normal Mendelian inheritance for a dihybrid cross
• Instead the phenotypic ratio will be more closely aligned to a monohybrid cross as the two genes are inherited as a single unit
• Linked genes may become separated via recombination (due to crossing over during synapsis in meiosis I)
• Linked genes are represented as ____________________

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10.2 Inheritance

10.2 U1 Gene loci are said to be linked if on the same chromosome

• The alleles for these traits were located on a shared chromosome (gene linkage) and hence did not independently assort
• Linked alleles could be uncoupled via recombination (crossing over) to create alternative phenotypic combinations, but these new phenotypes would occur at a much lower frequency

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3.4 Inheritance

Sources of mutations

3.4.U9 Radiation and mutagenic chemicals increase the mutation rate and can cause genetic diseases and cancer.

mutation in a oncogene

If a mutation occurs in an oncogenes it can become cancerous. In normal cells oncogenes control of the cell cycle and cell division.

http://en.wikipedia.org/wiki/Oncogene#mediaviewer/File:Oncogenes_illustration.jpg

uncontrolled cell division

tumour formation

malfunction in the control of the cell cycle

3.4 Inheritance

Review: 1.6.U6 Mutagens, oncogenes and metastasis are involved in the development of primary and secondary tumours.

A mutation is a change in an organisms genetic code.

A Gene mutation is a change in the nucleotide sequence of a section of DNA coding for a particular feature

Mutations can be classed as being beneficial, neutral or harmful. Most mutations are neutral or harmful.

Mutations that occur in body (somatic cells) remain within the organism. Mutations that occur in gametes can be inherited by offspring: this is how genetic diseases arise.

http://www.nature.com/scitable/topicpage/rare-genetic-disorders-learning-about-genetic-disease-979

3.4 Inheritance

3.4.U9 Radiation and mutagenic chemicals increase the mutation rate and can cause genetic diseases and cancer.

Radioactive isotopes released into the environment exposing humans and other organisms to potentially dangerous levels of radiation.

http://i.telegraph.co.uk/multimedia/archive/02446/hiroshima-bomb_2446747b.jpg

https://upload.wikimedia.org/wikipedia/commons/1/16/VOA_Markosian_-_Chernobyl02.jpg

3.4 Inheritance

Accident at Chernobyl nuclear power station

3.4.A4 Consequences of radiation after nuclear bombing of Hiroshima and accident at Chernobyl.

• A large area (4 km2) of pine forest downwind of the reactor turned brown and died.
• Horses and cattle near the plant died from radiation damage to their thyroid glands.
• Bioaccumulation of radioactive caesium in fish (Scandinavia and Germany) and lamb (Wales) - contaminated meat was banned from sale for years afterward.

3.4 Inheritance

Accident at Chernobyl nuclear power station

3.4.A4 Consequences of radiation after nuclear bombing of Hiroshima and accident at Chernobyl.

https://upload.wikimedia.org/wikipedia/commons/e/e9/The_patient%27s_skin_is_burned_in_a_pattern_corresponding_to_the_dark_portions_of_a_kimono_-_NARA_-_519686.jpg

https://upload.wikimedia.org/wikipedia/commons/f/f6/Hiroshima_girl.jpg

• Elevated rate of Leukemia (with the greatest impact in children and young adults)
• Elevated rates of other cancers
• No evidence of stillbirth or mutations in the children of those exposed to radiation

http://i.telegraph.co.uk/multimedia/archive/02446/hiroshima-bomb_2446747b.jpg

3.4 Inheritance

Nuclear bombing of Hiroshima

3.4.A4 Consequences of radiation after nuclear bombing of Hiroshima and accident at Chernobyl.

3.4 Inheritance

Larger samples give smaller standard deviation*, this in turn makes it easier to find a statistically significant result at a higher confidence level

In smaller samples anomalous values are more likely to skew the calculated mean and standard deviation

First to develop theory scientists must make deductions and test hypotheses: both processes rely on quantitative data.

Secondly It is not enough to just have numerical data, the sample size must be sufficiently large to be judged reliable.

3.4 Inheritance

To use statistical tests correctly and reach valid conclusions samples of quantitative data has to be sufficiently large

Nature of science: Making quantitative measurements with replicates to ensure reliability. Mendel’s genetic crosses with pea plants generated numerical data. (3.2)

3.4 Inheritance

Chi Squared

3.4.S2 Comparison of predicted and actual outcomes of genetic crosses using real data.

https://www.youtube.com/watch?v=5WGUbfzr31s (watch from 26:12 - 47:08)

https://www.youtube.com/watch?v=YfulqRdDbsg  Called Inside Chernobyl – quite a good film by an amateur filmmaker. There are some disturbing images.

https://www.youtube.com/watch?v=b8QY5gt1weE (watch 35:00 to 49:00 – study on the effects of radiation on Hiroshima survivors)

3.4 Inheritance

Application: Consequences of radiation after nuclear bombing of Hiroshima and accident at Chernobyl.

Drosophila breeding labs

3.4 Inheritance

10.2 Inheritance

10.2.A1  Completion and analysis of Punnett squares for dihybrid traits.

10.2 Inheritance

10.2.A1  Completion and analysis of Punnett squares for dihybrid traits.

• Null hypothesis (H0): There is no significant difference between observed and expected frequencies (i.e. genes are unlinked)

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• Alternative hypothesis (H1): There is a significant difference between observed and expected frequencies (i.e. genes are linked)

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10.2 Inheritance

10.2.A1  Completion and analysis of Punnett squares for dihybrid traits.

10.2 Inheritance

10.2 Inheritance

10.2.A1  Completion and analysis of Punnett squares for dihybrid traits.

• For all dihybrid crosses, the degree of freedom should be: (number of phenotypes – 1)In this particular instance, the degree of freedom is 3

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• A value is considered significant if there is less than a 5% probability (p < 0.05) the results are attributable to chance​

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10.2 Inheritance

10.2.U5  Chi-squared tests are used to determine whether the difference between an observed and expected frequency distribution is statistically significant.

• In sweet pea plants, the trait for purple flowers (A) is dominant to the trait for red flowers (a). �Similarly, the trait for long pollen (B) is dominant to the trait for round pollen (b). �Two heterozygotes are crossed, yielding the following frequencies for the F1 generation: �296 purple, long plants ; 19 purple, round plants ; 27 red, long plants ; 85 red, round plants 

�Activity: Use the chi-squared test to determine if these results are due to independent assortment. 

10.2 Inheritance

10.2.A1  Completion and analysis of Punnett squares for dihybrid traits.

10.2 Inheritance

10.2.S3  Use of chi-squared test on data from dihybrid crosses.

10.2 Inheritance

10.2.S3  Use of chi-squared test on data from dihybrid crosses.

10.2 Inheritance

10.2.U3 Variations can be discrete or continuous.​

Monogenic traits (characteristics controlled by a single gene loci) tend to exhibit discrete variation, with individuals expressing one of a number of distinct phenotypes. Eg Blood Type

10.2 Inheritance

You either have the characteristic or you don't.

10.2.U4  The phenotypes of polygenic characteristics tend to show continuous variation.

Polygenic traits (characteristics controlled by more than two gene loci) tend to exhibit continuous variation, with an individual’s phenotype existing somewhere along a continuous spectrum of potential phenotypes. Eg Skin colour.  multiple melanin producing genes

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10.2 Inheritance

There is a complete range of measurements from one extreme to the other

10.2.U4  The phenotypes of polygenic characteristics tend to show continuous variation.

10.2 Inheritance

10.2 U4 ​The phenotypes of polygenic characteristics tend to show continuous variation

An example of a polygenic trait is grain colour in maize (wheat), which is controlled by three gene loci. Grain colour can range from white to dark red, depending on the amount of pigment that is expressed

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10.2 Inheritance

Maize Grain Colour

10.2 U4 ​The phenotypes of polygenic characteristics tend to show continuous variation

One example of a polygenic trait that is influenced by environmental factors is human height.

Human height is controlled by multiple genes (polygenic), resulting in a bell-shaped spectrum of potential phenotypes

Environmental factors such as diet and health (disease) can further influence an individual human’s height

�Another example of a polygenic trait that is influenced by environmental factors is human skin colour. Skin colour is controlled by multiple melanin producing genes, but is also affected by factors such as sun exposure 

�

10.2 Inheritance

Height and Skin colour can be influenced by the environment

10.2 A3 Polygenic traits such as human height may also be influenced by environmental

10.2 Inheritance

https://www.youtube.com/watch?v=QOSPNVunyFQ

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Offspring with unlinked genes have an equal possibility of inheriting any potential phenotypic combination

• This is due to the random segregation of alleles via independent assortment

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Offspring with linked genes will only express the phenotypic combinations present in either parent unless crossing over occurs

• Consequently, the ‘unlinked’ recombinant phenotypes occur less frequently than the ‘linked’ parental phenotypes

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10.2 Inheritance

• https://www.youtube.com/watch?v=1S-b2C84Rww

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10.2 Inheritance

Sex Linked

10.2 A1 Morgan’s discovery of non-Mendelian ratios in Drosophila.

10.2 Inheritance

10.2 U3 ​Variation can be discrete or continuous.

Unlinked genes are on different chromosomes.

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10.2 Inheritance

10.2 U2 ​Unlinked genes segregate independently as a result of meiosis.

10.2 Inheritance

10.2 A1 Morgan’s discovery of non-Mendelian ratios in Drosophila.

10.2 Inheritance

10.2 S2 Identification of recombinants in crosses involving two linked genes.

10.2 Inheritance

Checkpoint

3.4 Inheritance Quiz

10.2 Inheritance Quiz

3.4 Inheritance Kahoot

10.2 Inheritance Kahoot