Cell Cycle

Question 1

cell cycle

Answer 1

• division of somatic cell into 2 daughter cells

- include: interphase & mitotic phase

Question 2

interphase occurences

Answer 2

• 3 phases: G1, S, G2
• chromosomes present as chromatin
• genes are transcribed to mRNA to make protein

Question 3

G1 phase

Answer 3

• last 8-10 hours
• growth and metabolism
• results: replicated chromosomes

Question 4

S phase

Answer 4

• last 6-8 hours
• DNA replicated + connected by centromere (sister chromatid)
• kinetochore proteins attach to centromere

Question 5

G2 phase

Answer 5

• last 4-6 hours
• enzymes and proteins are produced
• 2 sister chromatids attached at centromere

Question 6

mitosis

Answer 6

• 1 hour to complete
• growth and tissue repair
• involves: mitosis & cytokinesis
• results: 2 genetically identical daughter cells

Question 7

prophase

Answer 7

• chromatin is visible
• nuclear membrane & nucleoli disappear
• centrosomes go to opposite poles
• centromere have spindle fiber
• kinetochore attach to spindle microtubules

Question 8

metaphase

Answer 8

• sister chromatids lines in center of cell (metaphase plate)
• 46 chromosomes

Question 9

anaphase

Answer 9

• kinetochore fibers separate sister chromatids to pole

- cytokinesis begins

Question 10

telophase

Answer 10

• spindle break
• chromosomes uncoil > chromatin
• nuclear membrane & nucleoli appear
• results: 2 identical daughter cells

Question 11

meiosis

Answer 11

• sex cells
• 2n diploid to n haploid
• includes: meiosis I & meiosis II

Question 12

meiosis I

Answer 12

• separate homologous pairs

- diploid to haploid

Question 13

meiosis II

Answer 13

• separate sister chromatids
• result: 4 haploid gametes
• steps are the same as meiosis I

Question 14

prophase I

Answer 14

• synapsis
• tetrad: 4 sister chromatids
• crossing over (in synapsis)

Question 15

metaphase I

Answer 15

• tetrad align at plate

- microtubules attach to kinetochore

Question 16

anaphase I

Answer 16

• homologous pairs separate to poles

Question 17

telophase I

Answer 17

• each pole has haploid number chromosomes

Question 18

cytokinesis I

Answer 18

• overlaps telophase

- results: 2 haploid w/ 2 sister chromatids

Question 19

fertilization / development

Answer 19

haploid sperm + oocyte = diploid zygote

Question 20

pre-embryonic develoment

Answer 20

• first 2 weeks after fertilization
• zygote > embryo

cleavage division: dividing cell > morula (solid ball of cells)

Question 21

gestation

Answer 21

morula divides > blastocyst

- 5 days after fertilization

Question 22

blastocyst

Answer 22

• fluid filled cavity
• composed of:
  trophoblast cell: surround blastocyst + provide nourishment (becomes chorion)
  embryoblast: becomes embryo

Question 23

implantation

Answer 23

• attachment of blastocyst to endometrium
• 5-7 days post
• embryoblast > embryonic disk

disk consists of…

epiblast: rise to fetus
hypoblast: rise to yolk sac

Question 24

embryonic development

Answer 24

• 3rd-8th week post

- endoblast layer has ectoderm, mesoderm, endoderm

Question 25

what happens at the 4th-8th week post??

Answer 25

- major organs develop - heart beats - brains begins too develop - limb buds differenciate

Question 26

ectoderm

Answer 26

form nervous system + epidermal layer

Question 27

mesoderm

Answer 27

form muscle, bone, blood vessels, dermis

Question 28

endoderm

Answer 28

form epithelial layer of digestive, respiratory, urinary, reproductive tract & associated glands

Question 29

embryonic membranes consist of...

Answer 29

1) amnion 2) yolk sac 3) chorion 4) allantois

Question 30

amnion

Answer 30

- from epiblast | - filled cavity surrounding embryo (reduce disturbances)

Question 31

yolk sac

Answer 31

- from hypoblast | - produce early blood & germ cells

Question 32

chorion

Answer 32

- from trophoblast cells - fetal portion of placenta - surrounds embryonic membranes

Question 33

allantois

Answer 33

- pocketing of yolk sac | - umbilical cord & urinary bladder

Question 34

fetal development

Answer 34

- 9th-40th week

Question 35

inheritance

Answer 35

- transfer of genetically determined characteristics

Question 36

genetics

Answer 36

study of inheritance

Question 37

genes

Answer 37

segment of DNA on chromosome to direct protein synthesis

Question 38

chromosomes

Answer 38

DNA + histone proteins

Question 39

alleles

Answer 39

same locus on chromosome

Question 40

homozgous alleles

Answer 40

both gene copies encode same version of gene

Question 41

heterozygous alleles

Answer 41

both gene copies encode diff. version of gene

Question 42

dominant allele

Answer 42

fully exposed trait

Question 43

recessive allele

Answer 43

can be hidden by dominant

Question 44

genotype

Answer 44

genetic makeup of person

Question 45

phenotype

Answer 45

how genotype is expressed

Question 46

sex chromosomes: male & female

Answer 46

male: never homozygous (genotype depends on X carriers) female: can be homo/hetero (X chromosomes carry same gene at same loci)

Question 47

what is a punnett square?

Answer 47

predicts characteristic of offspring + probability of inheritance

Question 48

what is autosomal inheritance?

Answer 48

genes located on chromosomes 1-22