Cell division

Question 1

2 parts of a cell’s life cycle and amount of time spent in each

Answer 1

A: Interphase (90%)

• G1 = growth phase 1
• S-phase = Synthesize a copy of DNA
• G2= growth 2 phase

B: Mitosis & Cytokinesis (10%)

• Prophase
• Metaphase
• Anaphase
• Telophase & cytokinesis

Question 2

describe what occurs during prophase

Answer 2

• chromatin condenses to chromatids
• centrioles duplicate and move to poles
• spindle fibres form at centrioles and nuclear membrane dissolves

Question 3

describe what occurs during metaphase

Answer 3

chromosomes (paired chromatids) go to equatorial plate (middle)

Question 4

describe what occurs during anaphase

Answer 4

centromere breaks, spindle fibers shorten (guide chromatids to opposite poles)

Question 5

describe what happens during telophase/ cytokinesis

Answer 5

• chromatids reach poles and uncoil, reforming chromatin
• cleavage or cell plate splits cytoplasm & organelles in half
• nuclear membrane reforms

*plants: formation of cell plate before walls. no centrioles

Question 6

Mitosis produces __ __________ and

meiosis produces ___ ________

Answer 6

• 2 daughters (diploid)

- 4 gemetes (genetically different and haploid)

Question 7

in (meiosis/ mitosis), crossing over/ synapsis occurs in which phase

Answer 7

meiosis

prophase 1

Question 8

does the centromere break in meiosis 1 or 2

Answer 8

2

Question 9

Variation occurs due to : (list 3)`

Answer 9

1. crossing over during prophase 1
2. random movnt of the chromosomes at anaphase to the poles, produce millions of gene combinations in each gamete
3. chance determines which egg and sperm will meet

Question 10

in fertilization, what do the egg and sperm each contribute

Answer 10

1 sperm (n): contributes DNA only
\+ 
1 egg (n) contributes DNA and cellular organelles 
= 
zygote (2n)

Question 11

where do mitosis and meiosis each take place?

Answer 11

• mitosis (asexual reproduction): somatic/ body cells

- meiosis (sexual reproduction): in gonads (sex cells)

Question 12

• spermatogenesis (meiosis) forms __ sperm

- oogenesis (meiosis) forms __ egg and __ polar bodies

Answer 12

• 4

- 1 egg and 3 polar bodies

Question 13

identical twins

Answer 13

1 fertilized zygote splits into 2

same DNA = identical

Question 14

fraternal twins

Answer 14

2 fertilizations, same womb

different DNA`

Question 15

definition of a karyotype

Answer 15

stopping cell cycle in prophase, removing and pairing up maternal and paternal chromosomes to find non-disjuntion disorders (mono/trisomy)

Question 16

karyotype name of down’s syndrome

Answer 16

trisomy 21

Question 17

binary fission

Answer 17

dividing (mitosis) into 2 = halves

eg. bacteria and protozoans

Question 18

budding

Answer 18

outgrowth detach from cell (eg sea anemone)

Question 19

alteration of generations

Answer 19

sexual stage: produces haploid spores that turn into a plant by meiosis
asexual stage: produces haploid gametes by mitosis that fertilize to become diploid adult plant

Question 20

parthenogenesis

Answer 20

asexual reproduction: when an unfertilized female egg develops into an adult. The adults may be male or female ( ex daphnia)

Question 21

Gregory Mendel experiment

Answer 21

the study of heredity (how traits are inherited). experimented with garden peas

Question 22

gene definition

Answer 22

instructions for producing a particular trait

Question 23

allele definition

Answer 23

any one of the possible forms of a gene for the same trait

ie yellow or green are alleles for pea pod color

Question 24

locus definition

Answer 24

specific location of a gene on a chromosome

Question 25

genotype definition

Answer 25

the genes present (2 alleles make a genotype)

Question 26

phenotype definition

Answer 26

physical expression of the genotype

eg. tall or short
* environment has big effect on phenotype even though traits are controlled by gemes ( eg rabbit coat color)

Question 27

test cross

Answer 27

mixing an unknown phenotype with an unknown phenotype

Question 28

principle of independent assortment

Answer 28

genes on non-homologus chromosomes seperate independently from each other during meiosis

Question 29

theory of segregation

Answer 29

2n organisms inherit 2 genes for each trait

• these genes are located on pairs of homologous chromosomes that are separated during meiosis
• during meiosis, each gamete (n) only receives one gene per trait
• these genes recombine when the zygote is formed

Question 30

epistatic gene interaction

Answer 30

genes that interfere with expression of other genes (ie dog coat color)

Question 31

complementary gene interaction

Answer 31

2 different genes interact to produce a phenotype that neither is able to produce by itself
eg squash shapes

Question 32

pleiotropic gene interaction

Answer 32

a gene affects many different characteristics

ie sickle cell

Question 33

the further/ closer (locus) a gene is from a previous cross-over event increases the frequency of the next cross over happening

Answer 33

further apart

Question 34

only (males/ females) can transmit genetic mutations to their offsprint

Answer 34

females

Question 35

mendel’s principal of segregation states that alternate forms of a gene separate during

Answer 35

gamete formation

Question 36

how to differential sex- linked vs autosomal

Answer 36

sex linked= more boys affected than girls

Question 37

if affected individuals are in every generation of pedigree, it is ______

Answer 37

dominant

Question 38

____ is the shortest phase in meiosis/ mitosis

Answer 38

metaphase

Question 39

there is no centromere breakage after meiosis 1, so (haploid/ diploid) after meisosis 1

Answer 39

haploid

Question 40

examples of sex-linked inheritance to know (3)

Answer 40

red-green colorblindness, hemophilia, baldness

Question 41

barr-body

Answer 41

tightly condensed, inactive x chromosome in females

eg. calico cats- only female