Ch11 - Genetics

Question 1

What is Genetics?

Answer 1

The scientific study of heredity

Question 2

Genes vs Alleles

Answer 2

Genes: factors that determine traits/ characteristics (ex. hair color)
Alleles: different forms/versions of a gene (ex. black or brown hair color)

Question 3

What is a trait?

Answer 3

Specific characteristic that varies from individual to individual –> determined by alleles/ genes

Question 4

Dominant vs. Recessive

Answer 4

Dominant: organism will only have this form of the gene/ this trait
Recessive: organism will only have this form if dominant allele is not present

Question 5

Who came up with the Principle of Segregation and Independent Assortment?

Answer 5

Gregor Mendel - 1865

Question 6

Segregation vs Independent Assortment

Answer 6

Segregation: a gene has 2 alleles –> there is an equal distribution of alleles when forming gametes
Independent Assortment: genes for different traits segregate independently of each other and do not influence each others inheritance

Question 7

Define homologous

Answer 7

A couple of chromosomes (from both parents) that have the same size and copies of gene location

Question 8

Diploid vs Haploid

Answer 8

Diploid: A cell with 2 sets of chromosomes (1 from each parent)
Haploid: A cel with only 1 set of chromosomes

Question 9

What are the types of chromosomes? How many of each are present?

Answer 9

Autosomal chromosomes: 22 pairs
Allosomal/ sex chromosomes: X & Y chromosomes that determine sex

Question 10

What is the purpose of Meiosis?

Answer 10

A reduction division to cut number of chromosomes in half to form gametes for reproduction

Question 11

List of Meiosis cell cycle + what happens at each stage

Answer 11

1. Interphase 1: DNA duplication + Cell growth
2. Prophase 1: Homologous chromosomes come together –> tetrads
3. Metaphase 1: Homologous chromosomes line up at the equator
4. Anaphase 1: Homologous chromosomes are pulled apart by spindle fibers
5. Telophase + Cytokinesis: Cytoplasm is divided, forming 2 (duplicated) haploid cells
6. Prophase 2: chromatin condense to chromosomes
7. Metaphase 2: Chromosomes line up at the equator
8. Anaphase 2: sister chromatids are split apart
9. Telophase + Cytokinesis: Cytoplasm divides, forming 4 haploid cells

Question 12

What is a tetrad?

Answer 12

2 homologous chromosomes together

Question 13

What is crossing over? When does it happen? What is the purpose? Where does it happen?

Answer 13

• Exchange of genes between non-sister chromatid in a tetrad
• Prophase 1
• Bring variety in the gametes
• Chiasma

Question 14

What is the result of meiosis 1?

Answer 14

2 haploid cells w/ duplicated chromosomes

Question 15

What is the result of meiosis 2?

Answer 15

4 haploid cells

Question 16

How many gametes are formed in male & female?

Answer 16

Males: 4 sperm cells
Females: 1 egg & 3 polar bodies

Question 17

Why are polar bodies formed?

Answer 17

They allow for the reduction of chromosomes while preserving the cytoplasm for 1 egg

Question 18

How many combinations of zygotes are there?

Answer 18

2^n
n = # of paired chromosomes

Question 19

What is a zygote?

Answer 19

First cell produced when sperm and egg are fertilized

Question 20

Mitosis vs. Meiosis

Answer 20

Mitosis:
- Produce genetically identical cells from parents
- 1 cell division
- Results in 2 Diploid cells
- Occurs in all organisms
- Creates all somatic cells (not sex cells)
- No recombination/ crossing over
- In metaphase, chromosomes line up at equator
- In anaphase, sister chromatids separate

Meiosis
- Produce genetically diff. cells from parents
- 2 cell division
- Results in 4 haploid cells
- Occurs in only animals, plants, and fungi
- Creates only germ cells –> sperm, egg
- Involves recombination/ crossover for genetic variety
- In metaphase 1, homologous pairs line up at equator
- In anaphase 1, homologous pairs separate

Question 21

What is a karyotype? What is its function?

Answer 21

A visual diagram containing images of all chromosomes present in a cell
- used to identify any abnormalities in the chromosome count

Question 22

What is nondisjunction?

Answer 22

Chromosomes fail to divide properly resulting in too many or too little # of chromosomes in the final cell

Question 23

Trisomy vs monosomy

Answer 23

Trisomy: having an additional chromosome
Monosomy: having 1 less chromosome

Question 24

What is aneuploidy?

Answer 24

Combined term for trisomy + monosomy
- showing abnormal chromosome count

Question 25

List disorders relating to sex chromosomes

Answer 25

Turner Syndrome: Absence of X chromosome
Metafemale: Extra X chromosome (XXX)
Klinefelter Syndrome: Extra X chromosome in male (XXY)
Jacobs syndrome: Extra Y chromosome (XYY)

Question 26

List disorders relating to body chromosomes

Answer 26

Down Syndrome: Trisomy 21
Edwards Syndrome: Trisomy 18
Patau Syndrome: Trisomy 13