Chromosomes

Question 1

why do cells divide by mitosis?

Answer 1

to produce two cells that are genetically identical to the original cell (parent cell)

Question 2

what kind of cells does mitosis occur in?

Answer 2

in haploid and in diploid cells

Question 3

what is the 3 major functions of mitosis?

Answer 3

1. asexual reproduction
2. growth in multicellular organisms
3. cell replacement in multicellular organisms

Question 4

what needs to happen to a cell before it can divide?

Answer 4

• It needs to grow
• Copy its DNA
• Synthesize more proteins, organelles, etc

Question 5

what does DNA contain? how does DNA fit inside the nucleus?

Answer 5

• genetic information

- DNA is wrapped around proteins

Question 6

what are the proteins that associate with DNA? what is DNA + associated proteins called?

Answer 6

• histones

- chromatin

Question 7

what does chromatin make up? and what are those packaged into?

Answer 7

• chromosomes

- chromosomes are packaged into DNA molecules

Question 8

what happens to the chromatin when a cell prepares to divide?

Answer 8

it condenses to form distinct chromosomes

Question 9

how is Eukaryotic DNA organized?

Answer 9

into many linear chromosomes

Question 10

do all organisms have the same amount of chromosomes? how many chromosomes are there in the human genome?

Answer 10

• no, the number of chromosomes differs between organisms

- human genome has 23 chromosomes

Question 11

what is a genome? Is a genome a haploid or a diploid?

Answer 11

one complete set of genes (genetic material) present in a cell or organism
-Genome is the haploid set of chromosomes -> ie single set of unpaired chromosomes

Question 12

what do diploid cells contain? how many chromosomes are there in a human diploid cell?

Answer 12

• contain two copies of the genome

- 2n human cells contain 46 chromosomes

Question 13

what is a gene? where are they contained? how many of them are there?

Answer 13

• A gene is a discrete part of DNA with a particular sequence
• Chromosomes contain genes
• 100s – 1000s of genes in a chromosome

Question 14

before a cell divides, what must it duplicate? duplicated chromosomes consist of a pair of what? what are these called?

Answer 14

all of its chromosomes (DNA)

• consist of a pair of chromatids
• called sister chromatids ie. two identical copies of a DNA molecule

Question 15

1 chromatid is….

2 chromatids are…

Answer 15

replicated chromosome

sister chromatids –> replicated chromosomes

Question 16

sister chromatids are:

where are they chattered?

Answer 16

2 identical copies of a DNA molecule attached at the centromere

Question 17

what does the number of centromeres equal?

Answer 17

the number of chromsomes

eg. 1 centromere = 1 chromosome

Question 18

what does the number of centromeres equal?

Answer 18

the number of chromosomes

eg. 1 centromere = 1 chromosome

Question 19

how many copies of each chromosome do diploid cells have?

Answer 19

-2 copies of same chromosome

Question 20

what are matching pairs of chromosomes in diploid cells called? what are the same about them? what is different about them?

Answer 20

Homologous chromosomes
-same:
size
centromere location
genes controlling same inherited characteristics
genes in same location
-different:
may contain different versions of the same gene (different alleles)
one comes from maternal side, one comes from paternal side