Chromosomes, Dna, And Meiosis Notes

Front 1

chromosomes

Back 1

rod-shaped structures made of DNA and

protein.

Front 2

Chromosomes consist of two identical halves, what is each half called?

Back 2

sister chromatid

Front 3

Chromatids form as the DNA makes a _______ of itself before cell division.

Back 3

copy

Front 4

What is the name of the point in which two chromatids are attached?

Back 4

centromere

Front 5

What does each species have in each of their cells

Back 5

Each species has a characteristic number of chromosomes in each cell.

Front 6

How many total chromosomes do humans have and in how many pairs do they exist as?

Back 6

Humans have 46 total chromosomes that exist as 23 pairs.

Front 7

How are humans or animal chromosomes categorized as?

Back 7

They are categorized as either sex chromosomes or autosomes.

Front 8

In humans, sex chromosomes are either X or Y. Females have _____ chromosomes and males normally have an ____ chromosomes and a ____

chromosome.

All of the other chromosomes in an organism are___________.

Back 8

2 X *X and Y *autosomes

Front 9

*Every cell of an organism that reproduces by sexual reproduction has____ copies of each autosome.

*The organism receives a copy of each autosome from each_____ (one from the egg and one from the sperm).

Back 9

2 *parent

Front 10

What are the copies of each autosome called?

Back 10

homologous chromosomes, or homologs

Front 11

Homologous chromosomes

Back 11

They are the same size and shape and carry genes for the same traits

Front 12

diploids

Back 12

They are cells having two sets of chromosomes

Front 13

What is the number of diploids in humans?

Back 13

46

Front 14

Haploid cells

Back 14

Sperm and egg cells, which only contain one set of 23 chromosomes

Front 15

genes

Back 15

the sections of DNA in our chromosomes that contain instructions for our traits

Front 16

What are the sections called that DNA of each chromosome contain?

Back 16

the sections are called genes

Front 17

Because we get half of our chromosomes from our mother’s egg and half of our chromosomes from our father’s sperm, we have_____ forms of the genes for all of our characteristics (one on each homologous chromosome). (For example, mom could have passed down the blonde hair

color gene while dad could have passed down the brown hair color gene)

Back 17

two

Front 18

What is the shape of the DNA that makes up our chromosomes?

Back 18

double helix

Front 19

Why do we have 2 forms of the genes for all of our characteristics (one on each homologous chromosome)?

Back 19

Because we get half of our chromosomes from our mother’s egg and half of our chromosomes from our father’s sperm

(For example, mom could have passed down the blonde hair color gene while dad could have passed down the brown hair color gene).

Front 20

Meiosis

Back 20

the process of nuclear division that reduces the

number of chromosomes in new cells to half the number in the original cell

Front 21

gametes

Back 21

sex cells

Front 22

How many gametes does meiosis produce

Back 22

4 gametes

Front 23

What are human gametes?

Back 23

sperm cells and egg cells.

Front 24

What are the phases of interphase?

Back 24

Cells preparing to divide by meiosis undergo the G1, S, and G2

Front 25

Meiosis l

Back 25

The stages of the first cell division

Front 26

Meiosis ll

Back 26

the stages of the second cell division

Front 27

What happens in meiosis l and in meiosis ll?

Back 27

meiosis l - homologous chromosomes separate.

meiosis ll - chromatids separate.

Front 28

What happens in prophase l ?

Back 28

*Chromatin coils tightly into chromosomes.

*Spindle fibers appear

*Nucleolus and nuclear membrane disappear.

*Homologous chromosomes pair up, which is called a tetrad and crossing over occurs

Front 29

What does Crossing-over mean? and in does it occur in prophase l or ll?

Back 29

when portions of homologous chromosomes

exchange genetic material, occurs during prophase I and results in genetic variation.

Front 30

What happens in metaphase l ?

Back 30

*Tetrads line up randomly along the midline of the dividing cell

*Spindle fibers attach to the centromere of one homologous chromosome

*homologous pairs line up in the middle of the cell

Front 31

What happens in anaphase l ?

Back 31

Each homologous chromosome (consisting of two chromatids) moves to the opposite pole of the dividing cell.

Front 32

What happens in telophase I and cytokinesis?

Back 32

a. Chromosomes reach opposite ends of the cell

b. Cytoplasm division begins

c. New nuclear membranes form

d. 2 diploid cells are formed

Front 33

Meiosis ll

Back 33

*includes four phases that are just like mitosis ; sister chromatids separate.

*Four haploid cells result.

Front 34

sexual reproduction

Back 34

the formation of offspring through meiosis and the union of a sperm and an egg.

Front 35

Offspring produced by sexual reproduction are genetically_______ from the parents due to the combination of inherited genes and the ________ that occurs during meiosis.

Back 35

different

crossing over

Front 36

Where does fertilization occur?

Back 36

Fertilization occurs between gametes when 1 sperm is allowed into the egg to fertilize it.

Front 37

Because gametes are_____ (only 23 chromosomes in humans), the end result is a cell that is_______ (all 46 chromosomes that are found in humans).

Back 37

haploid

diploid

Front 38

Two chromosomes that carry genes for the same traits and are generally the same size and shape are called what?

Back 38

homologous chromosomes

Front 39

What are our first 22 pairs of homologous chromosomes called that do not determine our gender?

Back 39

autosomes

Front 40

The two identical halves that make up a duplicated chromosome are called?

Back 40

sister chromatid

Front 41

What are the chromosomes called that make up the last pair of our chromosomes and determine our gender?

Back 41

sex chromosomes

Front 42

The chromosomes number of a certain species of fish is 64. The chromosome number in the gametes would be ____ due to the process of ______.

Back 42

32 due to the process of meiosis

Front 43

If the fish with a chromosome number of 64 (from question 1) had offspring, the chromosome number of the offspring would be ____ due to the process of _____.

Back 43

64 due to the process of fertilization

Front 44

prophase ll

Back 44

*The chromosomes are not copied again between the two cell divisions.

*The nuclear membrane breaks down and spindle fibers form

Front 45

metaphase ll

Back 45

*chromosomes line up in a file line in the middle of the cell

Front 46

anaphase ll

Back 46

*chromatids are pulled apart

Front 47

telophase ll

Back 47

*4 haploid cell are formed from the original cell