Chapter 6- Chromosomes And Meiosis

Question 1

What are somatic cells? What are germ cells?

Answer 1

Cells that make up your body cells, tissues. Can copy themselves.

Germ-cells in your reproductive organs that develop into gametes

Question 2

How many chromosomes does a human have? How many pairs of chromosomes does a human have? What is a pair of chromosomes called?

Answer 2

46 chromosomes in 23 homologous pairs.

Question 3

What are autosomes? What is the 23rd homologous pair of chromosomes?

Answer 3

Chromosomes that contain genes for characteristics not directly related to the sex of the organism (1-22). The 23rd pair is the sex chromosome.

Question 4

What is the sex chromosome for a female? Male?

Answer 4

Female-XX

Male-XY

Question 5

What is fertilization?

Answer 5

The actual fusion of an egg and sperm cell into one nucleus

Question 6

What are diploid cells and what are examples of them?

Answer 6

Diploid cells are Ellis that have 2 copies of each chromosome, one from mother and father. Ex. Muscle cells, skin cells

Question 7

What are haploid cells and what are examples of them?

Answer 7

Haploid cells only have one copy of each chromosome. Ex. Gametes, sperm and egg

Question 8

Which parent’s gametes determines the sex of the child?

Answer 8

The male sperm either carries an X or a Y chromosome for the mother who has an X.

Question 9

What is meiosis? What is the result of meiosis?

Answer 9

Meiosis divides diploid cells into haploid cells. Meiosis produces gametes. Meiosis results in 4 haploid cells from 1 diploid cell.

Question 10

What occurs in prophase 1 and 2?

Answer 10

1. The nuclear membrane breaks down.
2. Centrosomes and centrioles move to opposite sides of the cell
3. Homologous chromosomes pair up

Question 11

What happens in metaphase 1 and 2?

Answer 11

1. Homologous chromosomes randomly line up along the cell equator

Question 12

What happens in Anaphase 1? Anaphase 2?

Answer 12

A1-The homologous pairs separate and move to opposite sides of the cell

A2-the sister chromatids separate and move to opposite sides of the cell

Question 13

What happens in telophase 2? What is the result?

Answer 13

1. A nuclear membrane forms around each set of chromosomes

2. RESULT–4 haploid cells that are genetically unique

Question 14

What are traits?

Answer 14

Inherited characteristics

Question 15

What is a purebred? What is a cross?

Answer 15

A type of organism whose ancestors are genetically uniform

Cross-the mating of two organisms

Question 16

What were Mendel’s 3 conclusions?

Answer 16

1. Traits are inherited as individual units
2. Organisms inherent 2 copies of each gene, one from each parent
3. Organisms can only donate one copy of each gene in their gametes

Question 17

What is a gene? What is a locus for a gene?

Answer 17

A piece of DNA that provides a set of instructions to a cell to make a certain protein.

Locus-each gene’s specific position on a pair of homologous chromosomes

Question 18

What is an allele? What is homozygous? Heterozygous?

Answer 18

One part of a genotype given from a parent.
Homo-two of the same alleles at a specific locus (AA, aa)
Heterosexual-two different alleles at a specific locus (Aa)

Question 19

What is a genotype? What is an example of a phenotype?

Answer 19

The genetic makeup of a specific set of genes. (The AA as being one)

Phenotype-purple flower pedals

Question 20

What is a testcross?

Answer 20

A cross between an organism with an unknown genotype and a recessive phenotype. The heterozygous genotype is used for the unknown (ex. Aa x aa)

Question 21

What is the law of independent assortment?

Answer 21

Allele pairs separate independently of each other during gamete formation

Question 22

What are the two causes for genetic variation? How many combinations of homologous pairs are there after meiosis? How many after fertilization?

Answer 22

1. Independent assortment
2. Random fertilization of gametes
   After meiosis- 8 million combos
   After fertilization-70 trillion combos

Question 23

What is genetic linkage?

Answer 23

Genes located close together on a certain chromosome tend to be inherited together.

Question 24

Homologous chromosomes are pairs of chromosomes containing genes that code for?

Answer 24

The same traits

Question 25

What is a haploid cell and an example? Diploid cell and an example?

Answer 25

Haploid-has only one set of chromosomes. Ex. A germ cell

Diploid-has both sets of chromosomes from each parent. Ex. A skin cell

Question 26

When does crossing over occur?

Answer 26

During prophase 1

Question 27

When does Mendel’s law of segregation state?

Answer 27

The two alleles for a trait SEGREGATE independently when gametes are formed

Question 28

What is the difference between Mendel’s experiments and those done by earlier researchers?

Answer 28

Mendel expressed the results of his experiments in terms of numbers