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From Flashcardlet > Biology Study Guide Ch. 5 Class Notes > Flashcards

Biology Study Guide Ch. 5 Class Notes Flashcards

0
Q

Porto-oncogene

A

Encodes proteins that promote the cell cycle and prevent a pop tonsils.

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1
Q

Cell cycle

A

Orderly set of stages that takes place between the time a cell divides.

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2
Q

Tumor suppressor genes

A

Encode proteins that stop the cell cycle and promotes a pop toss.

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3
Q

Benign

A

A

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4
Q

Malignant

A

A

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5
Q

Mitosis

A

Is nuclear division that produces tho-daughter nuclei, each with the same number and kinds of chromosomes as the parental nucleus.

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6
Q

Meiosis

A

Reducing chromosome number - occurs in any lifecycle that involves sexual reproduction and reduces the chromosome number such a way the daughter nuclei receives only one of each kind of chromosome.

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7
Q

Meiosis I

A

The homologous chromosomes come together as a pair at the metaphor plate.

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8
Q

Meiosis II - and fertilization

A

The sister chromatids separate the sister chromatids separate the daughter cells mature into gametes or sex cells sperm and egg – fuse together during fertilization.

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9
Q

Fertilization

A

Restores the diploid number of chromosomes.

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10
Q

Cell cycle

A

An orderly set of stages that takes place between the time the cell divides and the time the resulting cells divide.

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11
Q

Interphase - Most of the time 90% v. 20h

A
  • grows larger
  • Organelles double (g1)
  • DNA doubles (s)
  • 3 stages
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12
Q

G1

A

Accumulates materials needed for “s”

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13
Q

G o

A

Cell cycle arrested

- cell continues to perform its normal functions.

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14
Q

S

A

DNA replication

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15
Q

One chromosome

A

Chromatid

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16
Q

–>

A

2 sister chromatids

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17
Q

G2

A

Cell synthesizes proteins need for division

- micro tules for spindle

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18
Q

Mitosis

A

Division of the nucleus and genetic material.

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19
Q

Cytokinesis

A

Division of the cytoplasm

20
Q

1a. Spindle

A

Ensures orderly distribution of chromosomes to the daughter cell nuclei

21
Q

Prophase

A
  • division about to occur
  • centro some begin moving –> opposite ends of nucleus
  • spindle starts to appear
  • nuclear envelop begins to fragment
  • nucleoli begins to disappear
22
Q

Metaphase

A

Spindle has poles, aster, fibers

  • metaphase plate
  • chromosomes line up
23
Q

Anaphase

A 
Centromeres divide (sisters)
- sisters -->daughter move -->opposite poles
24
Q

Telophase

A
  • spindle disappears
  • nuclear envelope complex reassembles around the daughter chromosomes
  • nucleolus appears
  • cytokinesis underway
25
Q

Plants

A

No centrioles or aster

  • menstem tissue - shoot tip
  • root tip - tree girth
26
Q

Cytokinesis Plants

A
  • cytoplasmic cleavage - new cell walls built
  • division of cytoplasm - between daughter cells
    - rigid cell wall prevents furrow
27
Q

Meiosis

A
  • reducing chromosome number

- daughter cell receives only one of each kind

28
Q

Genetic variation

A
  • crossing over
  • exchange of genetic material between non-sister chromatids
  • independent assortment
  • homologous pairs separate during Anaphase 1
  • -> cells with different combinations of material and paternal chromosome.
29
Q

Fertilization

A
  • restores diploid number of chromosomes

- -> new individual

30
Q

Meiosis

A

Occurs in the life cycle of sexually reproducing organisms.

31
Q

Meiosis in Detail

A

Meiosis

32
Q

First Division

Meiosis 1 is divided into

A
  • Prophase 1
  • Anaphase 1
  • Metaphase 1
  • Telophase 1
33
Q

Meiosis helps ensure

A

Genetic variation

34
Q

Genetic variation occurs in two ways

A
  • crossing over

- independent assortment

35
Q

Meiosis 1

A
  • When homologous pairs separate, each daughter cell receives one member of the pair.
  • The cells are now haploid.
36
Q

Meiosis II and Fertilization

A
  • No replication of DNA occurs between Meiosis I And Meiosis II.
  • Centromes divide and sister chromatids migrate to opposite poles to become individual chromosomes.
  • Each of the four daughter cells produced has the haploid chromosome number.
  • Each chromosome is composed of one chromatid.
37
Q

Meiosis II and Fertilization

A
  • Fertilization
  • Daughter cells of meiosis mature into gametes.
  • Sperm and eggs fuse in fertilization.
  • Fertilization restores the diploid number.
  • (n) + (n) = (2n)
  • Creates a cell that will develop into a new individual
38
Q

Second Division

* Phases of Meiosis II

A
  • Anaphase II
  • sister chromatids separate and become daughter chromosomes that migrate toward the poles.
  • Telophase II
  • The spindle disappears
  • The nuclear envelope re-forms
  • Cytokinesis occurs.
39
Q

The importance of Meiosis

A
  • Meiosis produces haploid cells from diploid cells.
  • Genetic variation produces cells no longer identical to parental cell.
  • Genetic variation occurs in two was.
  • First, crossing between nonsister chromatids.
  • Second, the independent assortment of chromosomes during Anaphase I.
40
Q

Prophase I

A
  • Synapsids occurs, nuclear membrane breaks down.
  • Spindle appears, nuclear envelope fragments, and nucleoside disappears.
  • Homologues line up side by side and crossing over occurs.
  • After crossing over, chromatids held together are no longer identical
  • One has the original genetic material
  • One has recombined genetic material
41
Q

Metaphase I and Anaphase I

A
  • Metaphase I

- Homologous pairs line up at metaphase plate such that maternal or paternal member may be oriented toward either pole.

42
Q

The importance of Meiosis

A
  • Upon fertilization, bombing get of chromosomes from genetically different gametes help ensure offspring are not identical to parents.
  • This genetic variability is the main advantage of sexual reproduction.
  • Long-term, genetic variation increases the survival of a species.
43
Q

Occurrence

Meiosis occurs only at certain times of the life cycle of sexually reproducing organisms.

A
  • After the reproductive organs mature to produce gametes.

- Mitosis takes place almost continuously in all tissues as part of growth and repair.

44
Q

5.6 The Human Life Cycle

A
  • Both mitosis and meiosis are required.
  • At fertilization, a haploid (n) sperm and a haploid (n) egg fuse.
  • The resulting zygote has a diploid (2n) number of chromosomes.
  • The fetus divides by mitosis for growth and development.
  • After birth, mitosis allows continued growth and tissue repair.
45
Q

Spermatogenesis and Oogenesis in Humans

A
  • Meiosis in the testes of males in called spermatogenesis.
  • Produces sperm
  • Meiosis in the ovaries of females is called Oogenesis.
  • Produces eggs.
46
Q

Spermatogenesis occurs in testes of human males.

A
  • Process begins at puberty and continues throughout life.
  • Primary spermatocytes (2n) divide in meiosis 1 to form two secondary spermatocytes (1n).
  • Secondary spermatocytes divide in meiosis II to produce four spermatids.
  • Spermatids then mature to sperm (spermatozoa).
47
Q

Oogenesis

  • Begins in the fetus
  • Primary oocytes are arrested in prophase 1.
A
  • Resumes at puberty
  • One primary oocyte continues the process of meiosis during each menstrual cycle.
  • Primary oocyte (2n) divides in meiosis 1 to produce one secondary oocyte (1n) and one polar body (1n)
  • Division is unequal as secondary oocyte receives most of the cell contents and half the chromosomes.
48
Q

Oogenesis (continued)

A
  • If the secondary oocyte is fertilized, meiosis II will proceed.
  • Another unequal division will occur, with the egg receiving most of the cytoplasm.
  • A second polar body is also formed.
  • If the secondary oocyte is not fertilized, it disintegrates.

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