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Anatomy > Unit 4 - Cell Cycle, Mitosis, Meiosis > Flashcards

Unit 4 - Cell Cycle, Mitosis, Meiosis Flashcards

1
Q

Gametes

A
  • 23 different chromosomes (no pairs)
  • haploid
    -ova (eggs) and sperm
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2
Q

Zygotes

A

Fertilized egg
- Egg + sperm

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3
Q

Somatic cells

A
  • all body cells except for ones undergoing/resulting from meiosis
  • muscle, nerve
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4
Q

How many chromosomes are in somatic cells

A
  • 46 = diploid
  • 23 homologous pairs (one form each parent)
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5
Q

Homologous chromosomes

A
  • found in somatic cells
  • a chromosome pair (one from each parent) that are highly similar in length, centromere position, and have genes for the same trait (eye colour0 in the same location (locus)
  • may have alleles that code for proteins that produce alternate versions of that trait
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6
Q

Gene

A
  • unit of heredity
  • region of DNA which contains information for synthesis of a protein
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7
Q

Alleles

A
  • different versions of a gene
  • ex. Blue eyes (chromosome from one parent), brown eyes (chromosome from second parent)
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8
Q

Diploid cells

A

Contain 23 chromosomes from an ovum paired with 23 chromosomes from a sperm = 46 chromosomes

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9
Q

How are chromosomes numbered

A
  • 1 to 23
  • 1 to 22 = autosomal chromosomes (autosomes)
  • 23 = sex chromosome
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10
Q

Autosomal chromosomes

A
  • contain genes for somatic characteristics
  • ex. Hair colour, eye colour, height
  • each autosomal chromosome pair is not identical, but equivalent = homologous chromosomes
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11
Q

Sex chromosomes

A
  • contain genes that determine biological sex
  • XX = female
  • XY = male
  • X or Y from sperm
  • X from ovum
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12
Q

Mitosis

A
  • cell cycle for growth and repair of tissues
  • diploid somatic cell to 2 genetically indentical somatic diploid cells
  • 2 stages
    1. Interphase
    2. Mitotic/cell division phase
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13
Q

Interphase (mitosis)

A
  • G1, S and G2
  • cells spend most of their lives here
  • chromosomes are present as long thread-like chromatin strands
  • normal cellular metabolic activities occurring (ex. protein synthesis)
  • must have 2 of everything in order to divide (everything must duplicate)
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14
Q

G1 of interphase

A
  • growth and metabolism
  • Centrosome replication begins
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15
Q

G0 of interphase

A
  • cells that do not divide again once mature (stay in G1)
  • nerve and some muscle cells
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16
Q

S phase of interphase

A
  • chromosomes replicate, but are still present as long thread-like chromatin strands ( not individually visible)
  • ALWAYS occurs before cell division
  • Replicates are called sister chromatids
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17
Q

Sister chromatids during S phase

A
  • attached rot each other at an area of DNA called the centromere
  • Kinetochore form on each centromere
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18
Q

Kinetochore

A
  • site of attachment of spindle microtubules
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19
Q

G2 phase

A
  • Growth and metabolism
  • production of enzymes and other proteins needed for cell division
  • Centrosomes replication is completed
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20
Q

What does the mitotic phase involve

A
  1. Mitosis
  2. Cytokinesis
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21
Q

Mitosis

A

Is the division of nuclear material (chromosomes)

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22
Q

4 phases of mitosis

A
  1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase
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23
Q

Cytokinesis

A

Is the division of cytoplasm

24
Q

What happens when the mitotic phase ends

A
  • mitosis and cytokinesis are complete
  • resulting diploid cells to into interphase (G1)
  • cycle starts over
25
Q

What happens to chromosomes during mitosis

A
  • condense (thicken and coil)
  • become individually visible
26
Q

What happens to the nucleoli during prophase (mitosis)

A

They disappear

27
Q

What happens to the nuclear envelope during prophase (mitosis)

A

It breaks up

28
Q

Centrosomes during prophase (mitosis)

A

Move to opposite ends (poles) of the cell

29
Q

Spindle microtubules during prophase (mitosis)

A

Grow out of Centrosomes and attach to Kinetochore proteins of each sister chromatid, forming the spindle apparatus
- spindle begins to move chromosomes towards cell equator

30
Q

Metaphase (mitosis)

A

46 replicated chromosomes line up on cell equator

31
Q

What happens during anaphase (mitosis)

A
  • spindle microtubules shorten and pull the Kinetochores away from each other
  • causes separation of centromeres
  • results in separation of the sister chromatids into 92 individual chromosomes
32
Q

How many chromosomes migrate to each pole during anaphase (mitosis)

A

46

33
Q

When does cytokinesis being in mitosis

A

At the end of anaphase

34
Q

What happens to chromosomes during telophase (mitosis)

A

They uncoil into long thread-like strands of chromatin

35
Q

What reappears during telophase (mitosis)

A
  • nucleoli
  • nuclear envelope
36
Q

During what phase of mitosis do the spindles disassemble

A

Telophase

37
Q

During what phase of mitosis does cytokinesis end

A

At the end of telophase (after telophase is complete)

38
Q

What does meiosis produce

A

Gametes (ovum and sperm)
- 1 cell (diploid) produces 4 genetically unique gametes (each haploid)

39
Q

Stages of meiosis

A
  1. Interphase
  2. Meiosis I
  3. Meiosis II
40
Q

Interphase of meiosis

A

Is the same as interphase of mitosis

41
Q

Meiosis I

A
  • reduction division in which chromosome number changes from diploid to haploid)
  • stages:
    1. Prophase I
    2. Metaphase I
    3. Anaphase I
    4. Telophase I
    5. Cytokinesis
42
Q

Prophase I

A
  • homologous chromosomes attach together to form tetrads (4 chromatids in a row)
43
Q

Metaphase I

A
  • 23 tetrads line up along cell equator
44
Q

What happens to tetrads during anaphase I

A

They separate and migrate to opposite poles
- one homologous chromosome (with 2 sister chromatids) goes to each pole

45
Q

Do sister chromatids separate during anaphase I

A

NO!!!

46
Q

Telophase I

A
  • identical steps to telophase of mitosis but with 23 replicated chromosomes instead of 46
47
Q

After meiosis I and cytokinesis

A
  • each new cell has 23 different chromosomes (1/2 the number of- haploid)
48
Q

After meiosis I and cytokinesis do the cells have homologous chromosomes?

A

NO!!!

49
Q

What does each cell have after meiosis I and cytokinesis

A

A single copy of each autosomal chromosome and a single sex chromosome

50
Q

Meiosis II

A

Is the same as mitosis except it starts with 23 chromosomes instead of 46

51
Q

metaphase II

A

23 replicated chromosomes line up at equator

52
Q

Anaphase II

A

Sister chromatids split up and 23 chromosomes migrate to each pole

53
Q

Cytokinesis after meiosis II

A

Is the same as for mitosis/meiosis I
- begins in anaphase/anaphase I/anaphase II
- continues through telophase/telophase I/telophase II

54
Q

Why does meiosis occur

A
  • we need to turn diploid germ cells into haploid gametes (ova/sperm)
  • create zygotes
55
Q

Zygote

A

46 chromosome cell formed from a 23 chromosome haploid sperm cell combined with a 23 chromosome haploid ovum

Anatomy (17 decks)

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