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Biology Exam 3 > Chapter 11: Cell Cycle > Flashcards

Chapter 11: Cell Cycle Flashcards

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1
Q

What is Cell Division important for?

A

Growth: multicellular or colony of single-celled
Repair: Replaces lost or damaged cells
Reproduction: Asexual and Sexual

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2
Q

Describe Asexual and Sexual Reproduction

A

Asexual: One mother cell splits into daughter cells (no mate needed)
Sexual: Gametes (sperm and egg) come together to form a zygote (first cells of new individual)

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3
Q

Four Events of Cellular Division

A

Signal: To divide or not (RED LIGHT GREEN LIGHT)
Replication: Of the genetic material (make more of the same)
Segregation: Distribution of genetic material to daughter cells (split it up)
Cytokinesis: Division of cytoplasm

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4
Q

Cellular Division in Prokaryotes

A 
One cell (organism) to Two cells (organisms); the cell splits or divides
The overall process is called BINARY FISSION
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5
Q

FOUR events for Binary Fission

A

Reproductive Signal
Reproduction of DNA
Segregation of DNA
Cytokinesis

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6
Q

Reproductive signal in Binary Fission

A 
Favorable environment (carbohydrate source or mineral nutrients)
Can be as often as 20 minutes
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7
Q

Reproduction of DNA for Binary Fission

A

Most prokaryotes have single DNA molecules; ONE chromosome

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8
Q

Segregation of DNA in Binary Fission

A

DNA molecules moved to opposite ends of the cell

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9
Q

Cytokinesis

A

Begins AFTER chromosome replication
Plasma membrane pinches in (cleavage furrow) and new cells wall materials are deposited
Results: Separation into TWO new daughter cells
(basically even or uneven split of cytoplasm

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10
Q

What is a CHROMOSOME?

A

A DNA molecule with proteins bound to it

- contains genetic information of the cell

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11
Q

What does Chromatin contain?

A

1) A DNA molecule (extended)

2) Associated proteins

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12
Q

What is DNA?

A

DNA= Deoxyribonucleic Acid

  • Linear arrangement of nucleotides
  • A connected double helix (2 strands, Hydrogen bonded)
  • The largest molecule in the cell
  • All DNA in a typical human cell end to end is 2 meters
  • Thousands of attached proteins for packaging and protection
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13
Q

4 nitrogenous bases of DNA?

A

A C T G

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14
Q

What is a histone in DNA?

A

A protein that DNA wraps around for structural support and helps give shape to chromosome as it becomes packed/ PACKING PROTEINS
- in a 4 x 2 arrangement in each circle = 8 in each nucleosome

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15
Q

What is a nucleosome?

A

A nucleosome is the basic repeating unit of eukaryotic chromatin

  • the groups with 8 histones in it with DNA wrapped around it 2x (linker DNA)
  • comes together and gets packed to make chromatin
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16
Q

What is a GENE?

A

A sequence of DNA bases that codes for a polypeptide/ protein
(ex: GCATCAGAT)

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17
Q

How many different proteins does a cell have at any one time?

A

About 5000 different proteins

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18
Q

What are proteins used for? 4 things

A
  • Structural material (cytoskeleton)
  • Enzymes
  • Channels
  • Transporters
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19
Q

Chromosome

A

Condensed chromatin
- packaged for moving and distribution
HIGHLY COMPACT CHROMATIN (little squiggles to condensed)

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20
Q

What is a somatic cell?

A

All human cells other than sperm

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21
Q

Human chromosome number? Ploidy?

A

46 chromosomes, diploid (2n)

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22
Q

What are non-somatic cells? Ploidy?

A

Eggs or sperm cells, 23 chromosomes, haploid (n)

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23
Q

If the DNA code in each cell is the same, how do different cells develop?

A

Differentiation

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24
Q

What is differentiation?

How many genes are in a human?

A

Different genes/words are expressed and the outcome formed is different

  • different genes, different cell
  • about 19-24 thousand genes
    (ex: stem cell to fat cell)
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25
Q

How do gametes form a diploid zygote?

A

Fertilization of the egg and sperm (meiosis)

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26
Q

Define Cell Cycle

A

Procedure for cells that divide, eventually into two identical daughter cells

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27
Q

Longest stage of the Cell Cycle?

A

Interphase; about 90% of it

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28
Q

What is interphase?

A

When a cell is not actively dividing

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29
Q

How many phases are there of interphase? What are they?

A

3 phases; G1, S, and G2; G0

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30
Q

What is G0 (naught)?

A

When the cell is not dividing (like memory cells; cant make more of them)

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31
Q

What is G1?

A

Gap 1; normal living, preps for S phase

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32
Q

S phase?

A

Synthesis phase where the cell replicated genetic material; two copies now

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33
Q

G2?

A

Gap 2; prep for M phase, gets bigger and makes sure everything is in order

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34
Q

M phase?

A

Mitotic phase: When a cell IS dividing
- Mitosis or Meiosis
Followed by cytokinesis

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35
Q

What is the rule for meiosis?

A

It is only for egg and sperm (sexual reproduction)

36
Q

What are the two methods of Cell Division?

A

Mitosis and Meiosis

37
Q

What is the purpose of Mitosis?

A

To replicate cells, produces gametes

  • The number of chromosomes remains constant
  • the genetic information is the SAME
  • Produces 2 daughter nuclei
38
Q

Describe Meiosis

A
  • Changes chromosome number to one half: 23
    -Changes genetic information through different combinations (swaps)
  • Produces nuclei for egg and sperm
    Results in FOUR daughter cells
39
Q

Relationship between chromosomes and chromatin?

A

Chromosomes are TIGHTLY compacted chromatin

40
Q

What is genetic material during interphase?

A

Chromatin

41
Q

What do replication machinery proteins/ motor proteins do?

A

Make exact copies of DNA strands

42
Q

What begins mitosis?

A

chromatin condensing into chromosomes

43
Q

Mitosis

A

Division of nucleus

-nuclear division into 2 daughter nuclei

44
Q

What do prokaryotes perform instead of mitosis?

A

Binary Fission

45
Q

Phases of Mitosis (what are they and how many)

A

5 of them: Prophase, Prometaphase, Metaphase, Anaphase, Telophase

46
Q

Describe Prophase

A

First stage

  • PACKED DNA
  • nuclear envelope gone
  • centrioles migrate to opposite poles (sides) of cell
47
Q

S phase

A

DNA replicated

48
Q

S phase + G2=

A

A centrosome that duplicate and migrate using MTOCs

49
Q

What is a centrosome?

A

Made of two centrioles

50
Q

MTOCs?

A

Microtubule Organizing Center

51
Q

Meiosis

A

Process of TWO nuclear divisions= 4

- Reduces chromosome number to half (23; haploid)

52
Q

What is a main purpose of meiosis?

A

To create genetic diversity by only occurring in gonads

53
Q

Meiosis I components

A

Synapsis
Cross Over
Independent Assortment
Segregation

54
Q

Synapsis?

A

Pairing up of HOMOlogous chromosomes (23+23=46)

- FORMS TETRADS

55
Q

What are Tetrads?

A

Four sister chromatids next to each other (the X shape)

-allows for crossovers

56
Q

What is Cross over?

A

The equal exchange of chromosome material

57
Q

What are the four main phases of Meiosis I?

A

Same as Mitosis, except no prometaphase

- Prophase I, Metaphase I, Anaphase I, Telophase I

58
Q

Steps of Prophase I

A

-Chromatin condenses into chromosomes
- Nuclear envelope breaks down
-Chromosomes attach to mitotic spindle apparatus
(this is when synapsis occurs and forms tetrads)
-Cross overs

59
Q

Metaphase I

A

Chromosomes align at equator (M for MIDDLE)

  • crossovers can still occur
  • there is INDEPENDENT ASSORTMENT
60
Q

Anaphase I

A

homologous chromosomes pull APART towards opposite poles/sides

61
Q

What is Independent Assortment?

A

When the alleles can change and go where they want in the chromosomes (doesn’t matter it it is placed mother-father or father-mother

62
Q

Telophase I

A

-Nuclear envelope forms around separated/ segregated chromosomes
- they decondense into CHROMATIN
- Mitotic spindle apparatus dismantled
-HALF the amount of Chromies (haploid)
FOLLOWED BY CYTOKINESIS

63
Q

What is the interval between mitosis I and II called?

A

Interkinesis

64
Q

DNA after Meiosis I

A

Haploid chromosomes BUT DNA has been doubled

65
Q

What does meiosis II do to DNA?

A

Halves it!

66
Q

Stages of Meiosis II

A

Prophase II
Metaphase II
Anaphase II
Telophase II

67
Q

Prophase II steps

A
  • Duplicated centrosomes migrated to opposite poles
  • Chromatin condenses to chromosomes
  • nuclear envelope breaks down
  • chromosomes attach to mitotic spindle apparatus
68
Q

Metaphse II steps

A

-Chromosomes aligned at equator in the MIDDLE

69
Q

Anaphase II steps

A

Sister chromatids pulled APART from each other toward opposite poles

70
Q

Telophase II and Cytokinesis

A
  • Nuclear envelopes form around separated chromosomes
  • Chromosomes decondense into chromatin
  • Mitotic spindle apparatus DISMANTLED
  • Cells splits afte cytokinesis
  • 4 haploid daughter cells made
71
Q

Products of Meiosis I VS Meiosis II

A

Meiosis I: Goes from one cell to two with 23 in each

Meiosis II: Takes those two cells and separates them into 4 cells with 23 in each

72
Q

What is segregation and when does it occur?

A

the two alleles for a gene separate differently in anaphase I and II

73
Q

What is independent assortment and when does it occur?

A

random separation of homologous chromosomes in anaphase I

74
Q

What is crossing over and when does it occur?

A

The exchange of genes between homologous chromosomes during prophase I

75
Q

What is synapsis and when does it occur?

A

the pairing of homologous chromosomes in prophase I

76
Q

When are centrosomes duplicated and migrate?

A

S phase - duplicate

g2 phase - migrate

77
Q

where do the kinetochore microtubules attach to on the chromosome?

A

kinetochores and spindle poles

78
Q

what is the difference between the centromere and kinetochore?

A

the centromere is the general middle REGION and the kinetochore is the proteins that are at the center.

79
Q

What happens in prometaphase of mitosis?

A

sister chromatids become attached to the kinetochore (strandy part of the spindle), which are attached to the centrosome

nuclear envelope breaks

80
Q

can some cells permanently be in the G0 phase? example?

A

yes; neurons

81
Q

What is the G0 phase?

A

If the cell does not receive the go ahead for G1, it goes to G0 which is the resting phase

82
Q

What happens in the G2 phase?

A

many of the organelles and molecules required for cell division are produced

83
Q

how many somatic cell chromosomes do humans have? (haploid)

A

22 pairs

84
Q

how many non somatic chromosomes do humans have (sex chromosomes)? (haploid)

A

1 pair

85
Q

what allows cells to change from each part of the cell cycle? G1/s checkpoint? G2/M checkpoint?

A

CHECKPOINTS

  • If the cell will divide
  • If there is DNA damage; so bad genes aren’t passed on
86
Q

What happens in the G2 phase?

What is the G0 phase?

A
  • many of the organelles and molecules required for cell division are produced
  • If the cell does not receive the go ahead for G1, it goes to G0 which is the resting phase
87
Q

what happens with the egg cells?

A

So, cytokinesis splits the cytoplasmt unevenly; 3 smaller polar bodies are made (not useful for humans, fertilized in plants for endosperm), and one EGG is made (bigger, more cytoplasm

Biology Exam 3 (4 decks)

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