Insta-Review�Unit 5
Courtesy of @APBioPenguins
5.1: Meiosis
5.1: Meiosis
IST-1.F.1
Meiosis is a process that ensures the formation of haploid gamete cells in sexually reproducing diploid organisms—
a. Meiosis results in daughter cells with half the number of chromosomes of the parent cell.
b. Meiosis involves two rounds of a sequential series of steps (meiosis I and meiosis II).
IST-1.G.1
Mitosis and meiosis are similar in the way chromosomes segregate but differ in the number of cells produced and the genetic content of the daughter cells.
How many rounds of division in meiosis?
How many rounds of division in meiosis?
How many rounds of DNA replication?
How many rounds of DNA replication?
What phase does the crossing over take place?
What phase does the crossing over take place?
What phase does independent assortment take place?
What phase does independent assortment take place?
What is crossing over?
What is crossing over?
During prophase I, when the homologous pairs of chromosomes (maternal set and paternal set of a chromosome) pair, the non-sister chromatids (inner two) will overlap. The bonds will break and reform allowing the genetic material to switch chromatids. This results in recombinant DNA.
What is independent assortment?
What is independent assortment?
During metaphase I, the homologous chromosomes align on the metaphase plate. The independent assortment involves that the pairs independently align to face a pole of the cell. This means there are 2n different combinations that could result.
If parent cell is 2N, what is the ploidy of the daughter cell?
If parent cell is 2N, what is the ploidy of the daughter cell?
The following questions are comparing and contrasting mitosis and meiosis…��You should state the characteristics in mitosis AND meiosis.
Number of divisions
Number of divisions
Mitosis:
1 division
Meiosis:
2 divisions
Rounds of replication
Rounds of replication
Both mitosis and meiosis have 1 round of DNA replication before their division processes
Parent cell vs. daughter cell
Parent cell vs. daughter cell
Mitosis:
Parent – 2N
Daughter – 2N & genetically identical
Meiosis:
Parent – 2N
Daughter – N & genetically distinct
Number of daughter cells
Number of daughter cells
Mitosis:
2 daughter cells
Meiosis:
4 daughter cells
Crossing over?�Independent assortment?
Crossing over?�Independent assortment?
Mitosis:
Crossing over – No
Independent assortment – No
Meiosis:
Crossing over – Yes
Independent Assortment - Yes
Function of process?
Function of process?
Mitosis:
Growth & Development (responsible for organisms getting larger, replacing damaged cells, asexual reproduction, etc)
Meiosis:
Sexual reproduction (forms gametes)
At the end of which round of meiosis is the cell haploid?
At the end of which round of meiosis is the cell haploid?
5.2: Meiosis and Genetic Diversity
5.2: Meiosis and Genetic Diversity
IST-1.H.1
Separation of the homologous chromosomes in meiosis I ensures that each gamete receives a haploid (1n) set of chromosomes that comprises both maternal and paternal
chromosomes.
IST-1.H.2
During meiosis I, homologous chromatids exchange genetic material via a process
called “crossing over” (recombination), which increases genetic diversity among the resultant gametes.
5.2: Meiosis and Genetic Diversity
IST-1.H.3
Sexual reproduction in eukaryotes involving gamete formation—including crossing over,
the random assortment of chromosomes during meiosis, and subsequent fertilization of gametes—serves to increase variation.
What moves apart during anaphase I of meiosis I?
What moves apart during anaphase I of meiosis I?
What moves apart during anaphase II of meiosis II?
What moves apart during anaphase II of meiosis II?
When does crossing over take place?
When does crossing over take place?
How does crossing over affect linked traits?
How does crossing over affect linked traits?
Crossing over involves exchanging genetic material between nonsister chromatids.
During crossing over, the linked traits could be separated leading to being inherited independently.
What is the significance of crossing over?
What is the significance of crossing over?
What is the ploidy after homologous chromosomes separate?
What is the ploidy after homologous chromosomes separate?
Why is the cell haploid after homologous chromosomes separate?
Why is the cell haploid after homologous chromosomes separate?
Haploid involves having one set of chromosomes while diploid involves having two sets of chromosomes.
Homologous chromosomes are a set of maternal and a set of paternal chromosomes. So, if you separate the maternal and paternal set … you only have one set.
What processes increases genetic variation?
What processes increases genetic variation?
5.3: Mendelian Genetics
5.3: Mendelian Genetics
EVO-2.A.1
DNA and RNA are carriers of genetic information.
EVO-2.A.2
Ribosomes are found in all forms of life.
EVO-2.A.3
Major features of the genetic code are shared by all modern living systems.
EVO-2.A.4
Core metabolic pathways are conserved across all currently recognized domains.
5.3: Mendelian Genetics
IST-1.I.1
Mendel’s laws of segregation and independent assortment can be applied to genes that are on different chromosomes
5.3: Mendelian Genetics
IST-1.I.2
Fertilization involves the fusion of two haploid gametes, restoring the diploid number of chromosomes and increasing genetic variation in populations by creating new combinations of alleles in the zygote—
a. Rules of probability can be applied to analyze passage of single-gene traits from
parent to offspring.
b. The pattern of inheritance (monohybrid, dihybrid, sex-linked, and genetically linked
genes) can often be predicted from data, including pedigree, that give the parent
genotype/phenotype and the offspring genotypes/phenotypes.
Which macromolecule carries the genetic code?
Which macromolecule carries the genetic code?
All cells have ribosomes…
All cells have ribosomes…
What is the ribosome’s role in terms of gene expression?
What is the ribosome’s role in terms of gene expression?
The ribosome is the site of protein synthesis. This is the site where the genotype is expressed as a phenotype (the genetic information is used to create proteins)
If you take one gene from one organism and insert in another organism, the organism can synthesize the same protein.
If you take one gene from one organism and insert in another organism, the organism can synthesize the same protein.
Evolutionarily, why are you able to insert one gene into another & get same product?
Evolutionarily, why are you able to insert one gene into another & get same product?
All organisms share the same genetic code. It emerged in the common ancestor and is an ancestral trait.
Mendel described anaphase I as the law of …
Mendel described anaphase I as the law of …
Mendel described metaphase I as the law of …
Mendel described metaphase I as the law of …
What is the significance of gametes being haploid?
What is the significance of gametes being haploid?
When two gametes fuse (fertilization), the chromosome number is restored as diploid. If the cells were diploid, then after fertilization the zygote would be a tetraploid (too much genetic information)
The type of inheritance where the phenotype is intermediate
The type of inheritance where the phenotype is intermediate
For incomplete dominance, what phenotypic ratio do you expect in monohybrid cross?�Monohybrid by definition means two parents are heterozygous.
For incomplete dominance, what phenotypic ratio do you expect in monohybrid cross?�Monohybrid by definition means two parents are heterozygous.
What type of inheritance has a 3:1 ratio in monohybrid cross?
What type of inheritance has a 3:1 ratio in monohybrid cross?
Blood type phenotype can be A, B, AB, or O. This is an example of which type of dominance?
Blood type phenotype can be A, B, AB, or O. This is an example of which type of dominance?
What does it mean if inheritance is autosomal vs sex-linked?
What does it mean if inheritance is autosomal vs sex-linked?
Autosomal – the allele is on an autosome
Autosomes are the 22 chromosomes that do not determine sex assigned at birth
Sex-linked – the allele is on a sex chromosome
�What type of inheritance?
�What type of inheritance?
How do you know this is autosomal dominant?
How do you know this is autosomal dominant?
The trait does not skip generations. It is found in every generation. Every affected individual has an affected parent. (Dominant)
If it were x linked dominant, all females of affected father would be affected. The father only has an affected X chromosome, so the daughters would HAVE to inherit it and be affected
Mother has blood type O and Baby has blood type O��Which blood type could not be the father?
Mother has blood type O and Baby has blood type O��Which blood type could not be the father?
What is the phenotypic ratio of dihybrid complete dominance cross?��Dihybrid by definition is heterozygous for two alleles
What is the phenotypic ratio of dihybrid complete dominance cross?��Dihybrid by definition is heterozygous for two alleles
Pink is incomplete dominance (heterozygous)�Axial is complete dominance��Solve for the ratio of pink and axial in a dihybrid cross.
Pink is incomplete dominance (heterozygous)�Axial is complete dominance��Solve for the ratio of pink and axial in a dihybrid cross.
P(pink) x P(axial)
½ x ¾
3/8
Remember:
If it’s in the SAME Punnett square, you add…
probability of axial in a monohybrid cross is 3/4 because 1/4 AA and 2/4 Aa so P(axial) = 3/4
Remember:
If independent events or different Punnett squares, you multiply…
Probability of boy = 1/2
Probability of 2 boys = 1/2 x 1/2 = 1/4
(Note: boy assigned at birth)
Recommendation:
If you have anything higher than one allele for your Punnett squares, I HIGHLY recommend that you do 2x2 squares then multiply for what you are looking for
What type of inheritance
What type of inheritance
How do you know this is sex-linked recessive?
How do you know this is sex-linked recessive?
The trait skips the second generation (on the right). II-5 & II-6 are unaffected and then III-8 is affected (recessive)
Affected mother has affected songs (I-2, II-2, & II-4) sex-linekd
Note: female/male assigned at birth
5.4: Non-Mendelian Genetics
5.4: Non-Mendelian Genetics
IST-1.J.1
Patterns of inheritance of many traits do not follow ratios predicted by Mendel’s laws and can be identified by quantitative analysis, where observed phenotypic ratios statistically differ from the predicted ratios—
a. Genes that are adjacent and close to one another on the same chromosome may appear to be genetically linked; the probability that genetically linked genes will segregate as a unit can be used to calculate the map distance between them.
5.4: Non-Mendelian Genetics
IST-1.J.2
Some traits are determined by genes on sex chromosomes and are known as sex-linked traits. The pattern of inheritance of sex-linked traits can often be predicted from data, including pedigree, indicating the parent genotype/phenotype and the offspring genotypes/phenotypes.
IST-1.J.3
Many traits are the product of multiple genes and/or physiological processes acting in combination; these traits therefore do not segregate in Mendelian patterns.
5.4: Non-Mendelian Genetics
IST-1.J.4
Some traits result from non-nuclear inheritance—
a. Chloroplasts and mitochondria are randomly assorted to gametes and daughter cells; thus, traits determined by chloroplast and mitochondrial DNA do not follow simple Mendelian rules.
b. In animals, mitochondria are transmitted by the egg and not by sperm; as such, traits determined by the mitochondrial DNA are maternally inherited.
c. In plants, mitochondria and chloroplasts are transmitted in the ovule and not in the
pollen; as such, mitochondria-determined and chloroplast-determined traits are maternally inherited.
Cross between dihybrid and double recessive: what ratio do you expect?
Cross between dihybrid and double recessive: what ratio do you expect?
Parents: �Green, Smooth x Yellow, Wrinkled��Offspring:�Green, Smooth = 425�Green, Wrinkled = 50�Yellow, Smooth = 75�Yellow, Wrinkled = 450��How would you explain the offspring ratio differing from 1:1:1:1?
Parents: �Green, Smooth x Yellow, Wrinkled��Offspring:�Green, Smooth = 425�Green, Wrinkled = 50�Yellow, Smooth = 75�Yellow, Wrinkled = 450��How would you explain the offspring ratio differing from 1:1:1:1?
The genes are linked (located on the same chromosome)
Parents: �Green, Smooth x Yellow, Wrinkled��Offspring:�Green, Smooth = 425�Green, Wrinkled = 50�Yellow, Smooth = 75�Yellow, Wrinkled = 450��What process explains the recombinants made?
Parents: �Green, Smooth x Yellow, Wrinkled��Offspring:�Green, Smooth = 425�Green, Wrinkled = 50�Yellow, Smooth = 75�Yellow, Wrinkled = 450��What process explains the recombinants made?
Parents: �Green, Smooth x Yellow, Wrinkled��Offspring:�Green, Smooth = 425�Green, Wrinkled = 50�Yellow, Smooth = 75�Yellow, Wrinkled = 450��Calculate the recombinant frequency
Parents: �Green, Smooth x Yellow, Wrinkled��Offspring:�Green, Smooth = 425�Green, Wrinkled = 50�Yellow, Smooth = 75�Yellow, Wrinkled = 450��Calculate the recombinant frequency
12.5%
Step 1:
add the recombinants
50 + 75 = 125
Step 2:
divide by the total
125/1000 = 0.125
Step 3:
multiply by 100 to get into percent
0.125 * 100 = 12.5%
What is the difference between linked genes and SEX linked genes?
What is the difference between linked genes and SEX linked genes?
Traditionally, the linked will be on an autosome (non-sex chromosome) while the sex-linked is on a sex chromosome.
There’s two sex chromosomes (X & Y). The Y chromosome has the SRY gene which leads to “male characteristics”. So, if the allele is on a sex chromosome we say it’s sex linked.
A mutation in the mitochondrial DNA is from
A mutation in the mitochondrial DNA is from
How would you recognize mitochondrial genes on a pedigree?
How would you recognize mitochondrial genes on a pedigree?
Affected mother and ALL of the children are affected
5.5: Environmental Effects on Phenotype
5.5: Environmental Effects on Phenotype
SYI-3.B.1
Environmental factors influence gene expression and can lead to phenotypic
plasticity. Phenotypic plasticity occurs when individuals with the same genotype exhibit different phenotypes in different environments
What is phenotypic plasticity?
What is phenotypic plasticity?
Phenotype changes based on environment
This can be behavioral, physical, or morphological changes.
Why would the snowshoe hare change to brown earlier?
Why would the snowshoe hare change to brown earlier?
As temperatures increase, the snowshoe hares will synthesize different proteins to change their white fur color to brown. This is a direct result of global climate change.
As temperatures increase, the caterpillar population will hatch earlier. Predict how the hatching of its predator is affected?
As temperatures increase, the caterpillar population will hatch earlier. Predict how the hatching of its predator is affected?
Identify why many animals undergo plasticity
Identify why many animals undergo plasticity
5.6: Chromosomal Inheritance
5.6: Chromosomal Inheritance
SYI-3.C.1
Segregation, independent assortment of chromosomes, and fertilization result in genetic variation in populations.
SYI-3.C.2
The chromosomal basis of inheritance provides an understanding of the pattern of transmission of genes from parent to offspring.
SYI-3.C.3
Certain human genetic disorders can be attributed to the inheritance of a single affected or mutated allele or specific chromosomal changes, such as nondisjunction.
Which of these does not cause genetic variation?
Which of these does not cause genetic variation?
How does independent assortment cause genetic variation?
How does independent assortment cause genetic variation?
The homologous chromosomes align on the metaphase plate during metaphase I of meiosis I. These chromosomes align independent of each other. So, there’s a 50% chance which pole the chromosomes will “face”. If we are talking about 3 chromosomes, there’s 8 different combinations that could result. If there’s 4 chromosomes, there’s 16 different combinations. If there’s 5 chromosomes, there’s 32 different combinations.
I hope you see where we are going with this.
How does segregation cause genetic variation?
How does segregation cause genetic variation?
After alignment during anaphase I, the homologous chromosomes will separate (segregate) to the two poles. This allows half of the genetic information to go to one cell while the other half goes to the second cell. The two cells are not the same because they each received a different chromosome from the homologous
How does fertilization increase genetic variation?
How does fertilization increase genetic variation?
The unique cells formed due to independent assortment, segregation, and crossing over are fused leads to new combinations of alleles.
Note: sexual reproduction is describing the sperm/egg fusion. This can occur within a SINGLE organism like a flower that has both pollen (sperm) and ovary (egg)
Which phase of meiosis involved independent assortment?
Which phase of meiosis involved independent assortment?
Which phase of meiosis involved crossing over?
Which phase of meiosis involved crossing over?
Which phase of meiosis involved segregation?
Which phase of meiosis involved segregation?
There were two different theories about how traits were passed down from one generation to the next. How are traits inherited?
There were two different theories about how traits were passed down from one generation to the next. How are traits inherited?
What is nondisjunction?
What is nondisjunction?
Nondisjunction causes extra chromosomes to be inherited. On March 21, we celebrate National Downs Syndrome Awareness Day and Downs is caused by nondisjunction. But do you know which chromosome is involved?
Nondisjunction causes extra chromosomes to be inherited. On March 21, we celebrate National Downs Syndrome Awareness Day and Downs is caused by nondisjunction. But do you know which chromosome is involved?