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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
How do gametes form a diploid zygote?
Fertilization of the egg and sperm (meiosis)
26
Define Cell Cycle
Procedure for cells that divide, eventually into two identical daughter cells
27
Longest stage of the Cell Cycle?
Interphase; about 90% of it
28
What is interphase?
When a cell is not actively dividing
29
How many phases are there of interphase? What are they?
3 phases; G1, S, and G2; G0
30
What is G0 (naught)?
When the cell is not dividing (like memory cells; cant make more of them)
31
What is G1?
Gap 1; normal living, preps for S phase
32
S phase?
Synthesis phase where the cell replicated genetic material; two copies now
33
G2?
Gap 2; prep for M phase, gets bigger and makes sure everything is in order
34
M phase?
Mitotic phase: When a cell IS dividing - Mitosis or Meiosis Followed by cytokinesis
35
What is the rule for meiosis?
It is only for egg and sperm (sexual reproduction)
36
What are the two methods of Cell Division?
Mitosis and Meiosis
37
What is the purpose of Mitosis?
To replicate cells, produces gametes - The number of chromosomes remains constant - the genetic information is the SAME - Produces 2 daughter nuclei
38
Describe Meiosis
- 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
Relationship between chromosomes and chromatin?
Chromosomes are TIGHTLY compacted chromatin
40
What is genetic material during interphase?
Chromatin
41
What do replication machinery proteins/ motor proteins do?
Make exact copies of DNA strands
42
What begins mitosis?
chromatin condensing into chromosomes
43
Mitosis
Division of nucleus | -nuclear division into 2 daughter nuclei
44
What do prokaryotes perform instead of mitosis?
Binary Fission
45
Phases of Mitosis (what are they and how many)
5 of them: Prophase, Prometaphase, Metaphase, Anaphase, Telophase
46
Describe Prophase
First stage - PACKED DNA - nuclear envelope gone - centrioles migrate to opposite poles (sides) of cell
47
S phase
DNA replicated
48
S phase + G2=
A centrosome that duplicate and migrate using MTOCs
49
What is a centrosome?
Made of two centrioles
50
MTOCs?
Microtubule Organizing Center
51
Meiosis
Process of TWO nuclear divisions= 4 | - Reduces chromosome number to half (23; haploid)
52
What is a main purpose of meiosis?
To create genetic diversity by only occurring in gonads
53
Meiosis I components
Synapsis Cross Over Independent Assortment Segregation
54
Synapsis?
Pairing up of HOMOlogous chromosomes (23+23=46) | - FORMS TETRADS
55
What are Tetrads?
Four sister chromatids next to each other (the X shape) | -allows for crossovers
56
What is Cross over?
The equal exchange of chromosome material
57
What are the four main phases of Meiosis I?
Same as Mitosis, except no prometaphase | - Prophase I, Metaphase I, Anaphase I, Telophase I
58
Steps of Prophase I
-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
Metaphase I
Chromosomes align at equator (M for MIDDLE) - crossovers can still occur - there is INDEPENDENT ASSORTMENT
60
Anaphase I
homologous chromosomes pull APART towards opposite poles/sides
61
What is Independent Assortment?
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
Telophase I
-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
What is the interval between mitosis I and II called?
Interkinesis
64
DNA after Meiosis I
Haploid chromosomes BUT DNA has been doubled
65
What does meiosis II do to DNA?
Halves it!
66
Stages of Meiosis II
Prophase II Metaphase II Anaphase II Telophase II
67
Prophase II steps
- Duplicated centrosomes migrated to opposite poles - Chromatin condenses to chromosomes - nuclear envelope breaks down - chromosomes attach to mitotic spindle apparatus
68
Metaphse II steps
-Chromosomes aligned at equator in the MIDDLE
69
Anaphase II steps
Sister chromatids pulled APART from each other toward opposite poles
70
Telophase II and Cytokinesis
- Nuclear envelopes form around separated chromosomes - Chromosomes decondense into chromatin - Mitotic spindle apparatus DISMANTLED - Cells splits afte cytokinesis - 4 haploid daughter cells made
71
Products of Meiosis I VS Meiosis II
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
What is segregation and when does it occur?
the two alleles for a gene separate differently in anaphase I and II
73
What is independent assortment and when does it occur?
random separation of homologous chromosomes in anaphase I
74
What is crossing over and when does it occur?
The exchange of genes between homologous chromosomes during prophase I
75
What is synapsis and when does it occur?
the pairing of homologous chromosomes in prophase I
76
When are centrosomes duplicated and migrate?
S phase - duplicate g2 phase - migrate
77
where do the kinetochore microtubules attach to on the chromosome?
kinetochores and spindle poles
78
what is the difference between the centromere and kinetochore?
the centromere is the general middle REGION and the kinetochore is the proteins that are at the center.
79
What happens in prometaphase of mitosis?
sister chromatids become attached to the kinetochore (strandy part of the spindle), which are attached to the centrosome nuclear envelope breaks
80
can some cells permanently be in the G0 phase? example?
yes; neurons
81
What is the G0 phase?
If the cell does not receive the go ahead for G1, it goes to G0 which is the resting phase
82
What happens in the G2 phase?
many of the organelles and molecules required for cell division are produced
83
how many somatic cell chromosomes do humans have? (haploid)
22 pairs
84
how many non somatic chromosomes do humans have (sex chromosomes)? (haploid)
1 pair
85
what allows cells to change from each part of the cell cycle? G1/s checkpoint? G2/M checkpoint?
CHECKPOINTS - If the cell will divide - If there is DNA damage; so bad genes aren't passed on
86
What happens in the G2 phase? What is the G0 phase?
- 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
what happens with the egg cells?
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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