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Anatomy > Topic 4: The Cell Cycle > Flashcards

Topic 4: The Cell Cycle Flashcards

1
Q

Gametes

A

23 different chromosomes = haploid (n)

includes ova (eggs) + sperm

  • sex cells
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2
Q

Somatic Cells

A

includes all cells of body except cells undergoing/resulting from meiosis

eg: muscle cell, nerve cell, etc.

46 chromosomes = diploid (2n)

= 23 homologous pairs

soma= body

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3
Q

Homologous Chromosomes

A

a chromosome pair (1 from each parent) that are identical in length, centromere position, and have genes for the same trait (e.g. eye colour) in the same location (locus)

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4
Q

Gene

A

a unit of heredity
= a region of DNA which contains information for synthesis of proteins

*how we pass on genetic info from one person to the next

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5
Q

alleles

A 
different	versions (alleles)	of	that	gene that code for													
different	versions	of that trait.

§ e.g. blue eyes (chromosome from Dad), brown eyes
(chromosome from Mom)

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6
Q

What does each somatic cell contain?

A

23 different chromosome pairs

23 chromosomes from mom (ovum) paired with 23 chromosomes from dad (sperm)

= 46 chromosomes (diploid/2n somatic cell)

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7
Q

autosomal chromosomes (autosomes)

A

1 to 22

¦ contain genes for somatic characteristics

¦ e.g. hair and eye colour, height, etc

¦ each autosomal chromosome pair is not identical, but
equivalent= homologous chromosomes

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8
Q

sex chromosome

A

23
¦ contain genes that determine sex, XX=F XY=M

¦ X or Y from Dad

¦ X from Mom

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9
Q

What is the purpose of mitosis?

A

for growth + repair of tissues

to produce somatic cells

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10
Q

What does mitosis result in?

A

2 genetically identical daughter cells

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11
Q

List the stages of the cell cycle:

A

1) Interphase

2) Mitotic (M)/Cell Division phase

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12
Q

List the stages within Interphase:

A

G1,
S,
G2 phases

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13
Q

Interphase

A

chromosomes present as chromatin

normal cellular metabolic activities occurring e.g. protein synthesis

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14
Q

G1 Phase

A

growth, metabolism

centrosome replication begins

Note: in some cells that do not divide again once mature, (i.e. remain
in G1) – in these cells it is termed G0 phase

¦ e.g. nerve + some muscle cells

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15
Q

S Phase

A

chromosomes replicate, but are still present as chromatin (not individually visible)

ALWAYS occurs before division (mitosis and meiosis)

kinetochore proteins are produced

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16
Q

sister chromatids

A

replicates formed during S phase

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17
Q

centromere

A

area of DNA where sister chromatids attach to one another

18
Q

kinetochore proteins

A

(produced during S phase) attach to each centromere to form the kinetochore

19
Q

kinetochore

A

protein + DNA complex,
1/chromatid meaning 1 on each side)

site of attachment of spindle microtubules

20
Q

G2 Phase

A

growth, metabolism

production of enzymes & other proteins needed for cell division

centrosome replication completed

21
Q

What does the Mitotic Phase involve?

A

a) mitosis

b) cytokinesis

22
Q

mitosis

A

= division of nuclear material (chromosomes)

4 phases, but continuous cycle!

i. Prophase
ii. Metaphase
iii. Anaphase
iv. Telophase

23
Q

cytokinesis

A

division of cytoplasm

24
Q

when mitotic phase ends:

A

mitosis & cytokinesis complete

daughter cells go into interphase (G1)

cycle starts over

25
Q

Prophase

A 
chromosomes condense	(thicken,	coil)	from chromatin	form - become individually	
visible

nucleoli disappear and nuclear envelope breaks up

centrosomes move to either pole

microtubules	form spindle	apparatus (starting at centrosomes)	+	attach	to
kinetochore	proteins (called	kinetochore	microtubules)

Spindle moves chromosomes toward cell equator

26
Q

Metaphase

A

46 chromosomes line up on cell equator

27
Q

Anaphase

A

as the spindle microtubules shorten, the kinetochores are pulled away from each other – causing separation of centromeres, which results in separation of the chromatids

46 chromatids migrate to each pole

cytokinesis (division of cytoplasm) begins

28
Q

Telophase

A

chromosomes uncoil to chromatin

nucleoli, nuclear envelope reappear

spindle disassembles

cytokinesis completes (or may end after telophase ends)

29
Q

Meiosis

A

reproductive nuclear division

30
Q

meiosis produces

A

gametes (= ovum + sperm)

1 cell (diploid, 2n) produces

4 genetically dissimilar gametes (each haploid, n)

31
Q

What are the stages of Meiosis

A

involves: interphase (G1, S, G2) followed by 2 cell divisions:
1) Meiosis I, immediately
followed by
2) Meiosis II

between meiosis I + II = interkinesis NOT interphase (no DNA replication)

32
Q

Meiosis I

A

(reduction division = 2n to n)

events same as in mitosis

33
Q

Prophase I

A

i. homologous chromosomes attach together = tetrads (4 chromatids in a
row)

ii. crossing over occurs
• piece of 1 chromatid exchanges with matching piece from a chromatid of the homologous chromosome i.e. non-sister chromatid

  • acts to increase genetic diversity
  • e.g. you pass on your dad’s black hair with your mom’s blue eyes
34
Q

Metaphase I

A

23 tetrads line up along cell equator

35
Q

Anaphase I

A

tetrads (homologous chromosome pairs) separate and migrate to opposite poles

i.e. 1 homologous chromosome (with 2 sister chromatids) goes to each
pole chromatids DON’T separate

36
Q

Telophase I

A

same as mitosis telophase

spindle disassembles

nucleolus and nuclear envelope reappear

chromosomes uncoil to chromatin

37
Q

After Meiosis I and cytokinesis:

A

each new cell has 23 different chromosomes (½ the number of Xms) = haploid (n)

these cells DO NOT have homologous chromosomes

chromosome 1 – 23 from Mom OR Dad (randomly segregated)

38
Q

Meiosis II

A

same as mitosis except with 23 chromosomes instead of 46

a) prophase II
b) metaphase II - 23 chromosomes line up at equator
c) anaphase II - 23 chromatids migrate to each pole
d) telophase II

¦ cytokinesis – same for mitosis/meiosis (begins in anaphase/anaphase I/anaphase II,
and continues through telophase/telophase I/telophase II)

39
Q

Where does meiosis take place in the body?

A

In the gonads

ovaries= female

testes= males

40
Q

Why meiosis?

A

Need to turn diploid germ cells into haploid gametes

41
Q

Fertilization

A

— spermatozoon (n) contacts and penetrates 2o oocyte (n) = fertilization

— triggers completion of meiosis II in 2o oocyte

– forms ovum (egg)

— then ♂ + ♀ pronuclei unite

— new cell = zygote (2n)

42
Q

pronucleus

A

nucleus of sperm/egg post-fertilization but prior to fusion

Anatomy (19 decks)

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