Unit 6- How are genetics passed on?

Summary of LuLu Data Sets 1-2

→ Lulu (630) likely left the Reifontein pride to save her cubs from being killed by the new males → she took her cubs to the Homob pride

→ The prides are fairly close together in location, so movement between the two would be fairly easy.

• Males migrate the most
• Females stay with their original pride
• Babies moved from one pride to another

Who is the mother and father of the cubs?

SPERM

​

EGG

​

+

ZYGOTE

Chromosomes and where they come from

Notes about chromosome basics

What is a Karyotype?

A karyotype is a picture displaying the chromosomes of one organism

• Lions have 38 chromosomes = 19 pairs
• Humans have 46 chromosomes = 23 pairs

Chromosomes are composed of tightly coiled DNA and proteins

​

​

Sex Determination

​

​

• 22 pairs are homologous (look alike) – called autosomes – determine body traits

1 pair is the sex chromosomes – determines sex (male or female)

​

• Females – sex chromosomes are homologous (look alike) – label XX

Males – sex chromosomes are different – label XY

�

​

*Aka autosomal chromosomes

(Are pairs 1-22)

(Pair 23)

• ​

Is this lion a boy or a girl? How do you know?

Is this lion a boy or a girl? How do you know?

Homologous Chromosomes are arranged based on:

• Size (Length)
• Position of Centromere (center of the chromosome)
• Banding Pattern (represented by the bases of the DNA strand)

​

-ONE chromosome comes from the mother

-ONE chromosome comes from the father

Homologous Chromosomes: 2 chromosomes in a pair

• Gene = a section of the chromosome that codes for a trait
• Locus = a gene’s address
• Which chromosome it is found on & where on the chromosome it’s found
• Alleles = different versions (kinds) of a gene
• Ex. Eye color has many alleles (blue, black, brown, & green)

Genotypes VS Phenotypes

Genotypes (AA, Aa or aa):

• 2 Alleles
• 1 from each parent
• Genotypes can be:
• Heterozygous = two different alleles (ex: Aa)
• Carrier or Hybrid
• Homozygous = two of the same alleles (ex: AA or aa)
• purebred

​

Phenotypes

• What you have as a trait
• EX: red hair, blue eyes, can roll your tongue, etc.

• Dominant = an allele that can hide another allele
• You will always see it!
• Written with a capital letter
• Recessive = an allele that can be hidden by a dominant allele
• Don’t always know you have it
• Written with a lowercase letter

Meiosis Major Terms

Meiosis: required for reproduction. Is cell division that halves the number of chromosomes in the parent cell and produces 4 unique gamete cells

Germ Cells: A cell that develops into a reproductive cell (egg in females, sperm in males)

Gametes: Reproductive cells. Haploid cells where each only carries one copy of a chromosome

Fertilization: The process of combining the male gamete (sperm) with the female gamete (ovum)

​

Haploid: The presence of a single set of chromosomes

Diploid:The presence of 2 complete sets of chromosomes

Crossing Over:The exchange of genetic material between non sister chromatids

​

Honors only vocab

Independent Assortment:The formation of random combinations of chromosomes

Nondisjunction: An error in cell division. The failure of homologous chromosomes to separate properly. Daughter cells will not have the proper number of chromosomes

​

Let’s connect the terms by going through meiosis

Meiosis

Mitosis vs. Meiosis

MITOSIS

• Occurs in Somatic Cells (Body Cells = skin, muscle, blood)
• Purpose: Repair or Growth
• One Division occurs
• Results with genetically identical cells

​

***NO crossing over, NO independent assortment

​

The only way the genetic material changes in these types of cells is if there is a mutation (mutations are errors that occur during DNA replication)

MEIOSIS

• Occurs in Germ Cells (Sex cells/Gametes = sperm and egg)
• Purpose: Reproduction
• Two Divisions occur
• ½ the amount of chromosomes
• When fertilization occurs zygote will have 46 chromosomes (for humans)
• Results in genetically different cells
• 1 cell forms into 1 egg, 3 cells are polar bodies (absorbed by the body - remember a female releases 1 egg a month)
• 4 cells form into 4 sperm

Crossing over, Independent Assortment and Fertilization lead to an increase in genetic variation (or diversity)

Analyze Data Set #5 - Explanation of Section A

FCA26 is a GENE Locus

A, B, and C are the ALLELES possible for this gene

Data Set 5 Takeaways