The Cell Cycle

Question 1

The Cell Theory

Answer 1

3 Central Principles:

• All organisms are composed of one or more cells
• The cell is the basic unit of life of structure and function of all organisms
• All cells arise form pre-existing cells

Question 2

The Cell Cycle

Answer 2

series of events which describes the process by which cells divide.

Question 3

Interphase

Answer 3

• “resting stage” of the cell ycle
• actively metabolizing and synthesizing materials and components needed for cell division

Stages:
A. Gap 1 (G1) Phase
B. S Phase
C. Gap 2 (G2) Phase

Question 4

Gap 1 Phase (G1)

Answer 4

cells increase in size and synthesize proteins and enzymes needed for DNA replication

*G0 Phase- cells become specialized and are no longer active

Question 5

S Phase

Answer 5

cells perform DNA replication; creating two sets of DNA

Question 6

Gap 2 Phase (G2)

Answer 6

Microtubule Synthesis

cells synthesize materials such as microtubules necessary for cell division

Question 7

Interphase Processes

Answer 7

DNA Replication and Protein Synthesis

Question 8

A. DNA Replication

Answer 8

• DNA———> DNA
• cell’s DNA makes a duplicate of itself with the aid of various enxymes
• Helicase (unzipper)
• Single Strand Binding Protein (holder of two strands)
• DNA Polymerase (synthesizer)
• Gyrase (reliever)
• Ligase (joins)
• Template Strand (original)
• Leading Strand (continuous)
• Lagging Strand (fragments)

Question 9

Helicase

Answer 9

“unzips” the two DNA strands

Question 10

Single Strand Binding Protein

Answer 10

holds the two strands

Question 11

DNA Polymerase

Answer 11

synthesizes new DNA strand using the original (3’—>5’); producing a complimentary strand (5’——> 3’)

I. DNA Polymerase I -synthesize lagging strand
II. DNA Polymerase III synthesize leading strand

Question 12

Gyrase

Answer 12

relieves the strain cause from uncoiling

Question 13

Ligase

Answer 13

joins the pieces of Okazaki Fragments together

Question 14

Template Strand

Answer 14

original strand

Question 15

Leading Strand

Answer 15

new strand, synthesized continuously

Question 16

Lagging Strand

Answer 16

new strand. synthesized in fragments

Question 17

B. Protein Synthesis

Answer 17

process by which cells synthesize proteins
relies heavily on the different RNA species: mRNA, tRNA, rRNA

Processes: Transcription and Translation

Question 18

Transcription

Answer 18

• DNA———> RNA
• formation of RNA from DNA that encdoes functional protein
• inside the nucleus

Question 19

Translation

Answer 19

• RNA———> Protein
• formation of proteins from an RNA strand
• Each mRNA strand is called a “ codon” which corresponds to one amino acid
• Occurs in cytoplasm with ribosomes

DNA-code
mRNA-codon
tRNA-anticodon

Question 20

mRNA

Answer 20

“Messenger RNA”

synthesized during transcription; RNA copy of the DNA coding for the protein

Question 21

tRNA

Answer 21

“Transfer RNA”

delivers amino acids to the ribosomes, the site of translation

Question 22

rRNA

Answer 22

“Ribosomal RNA”

component of ribosomes

Question 23

CELL DIVISION

Answer 23

Mitosis & Meisosis

Question 24

Mitosis

Answer 24

-occurs in somatic or body cells
-undergoes division for the purpose of growth, tissue repair and cell proliferation
-Phases:
A. Prophase
B. Metaphase
C. Anaphase
D. Telophase

Question 25

Prophase

Answer 25

- chromatin condenses into chromosomes - centrioles migrate to opposite poles - nuclear envelope disintegrates and nucleolus disappears

Question 26

Metaphase

Answer 26

- centrioles and spindle fibers attach to chromosomes at the "kinetochore" - chromosomes are assembled at the metaphase plate or equatorial plate

Question 27

Anaphase

Answer 27

- sister chromatids break at the centromeres | - spindle fibers pull the chromatids at opposite poles

Question 28

Telophase

Answer 28

- sister chromatids reaches the opposite poles - nuclear envelope starts to form - chromsomes uncoil - nucleoli appear *Cytokinesis-separation of the cytoplasm of the daughter cells

Question 29

Kinetechore

Answer 29

point of attachment of spindle fiber

Question 30

Centromere

Answer 30

entire middle region where kinetochore is found

Question 31

Meiosis

Answer 31

- occurs in germ cells to produce gametes - main purpose is to generate haploid sex cells - Meiosis I & Meiosis II

Question 32

Meiosis I

Answer 32

- reductional division - Mother cell: diploid - Daughter cell: haploid; genetically unique from the mother cell ``` Parts: Prophase I (L, Z, P, D) Metaphase I Anaphase I Telophase I ```

Question 33

Prophase I

Answer 33

Parts: a. Leptotene- condensation of chromatins b. Zygotene- pairing of homologous pair c. Pachytene- crossing over of homologous pair and exchange of genetic material d. Diplotene- homologous pair appear as tetrads

Question 34

Metaphase I

Answer 34

tetrads line up at the equatorial plate

Question 35

Anapahase I

Answer 35

homologous pair separate and migrate to opposite poles

Question 36

Telophase I

Answer 36

cytokinesis begins, giving rise to two haploid daughter cells

Question 37

Meisosis II

Answer 37

-similar process to that of Meiosis. -However initial cells are haploid instead of daughter cells giving rise to another set of haploid cells -Parts: Prophase II Metaphase II Anaphase II Telophase II

Question 38

Mitosis Cells

Answer 38

``` Mother Cell: Somatic No. of Divisions: 1 Ploidy of Daughter Cells: Diploid Genetic Variation: - Purpose: Growth, Repair ```

Question 39

Meiosis Cells

Answer 39

``` Mother Cell: Germ cells No. of Divisions: 2 Ploidy of Daughter Cells: 4 Genetic Variation: + Purpose: Produce Gametes ```

Question 40

Gametogenesis

Answer 40

Process: 1. Growth and Maturation 2. Meiosis 3. Differentiation Male: Spermatogenesis Female: Oogenesis

Question 41

Spermatogenesis

Answer 41

Organ Involved: Testes Formation of Polar Bodies: No Daughter Cells : 4 spermatozoa Time of Occurrence: starts at puberty

Question 42

Oogenesis

Answer 42

``` Organ Involved: Ovaries Organ Involved: Ovary Formation of Polar Bodies: Yes Daughter Cells : 1 ovum, 3 polar bodies Time of Occurrence: begins before birth, pauses, continues at puberty ```

Question 43

Liptotene

Answer 43

"Condensation"

Question 44

Zygotene

Answer 44

"Pairing"

Question 45

Pachytene

Answer 45

"Crossing over"

Question 46

Diplotene

Answer 46

"Formation of tetrads"