Chapter 8: Cell Reproduction

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1

Chromatin

uncoiled DNA (interphase)

2

Chromosome

coiled DNA
-coiled because of histones

3

Histones

proteins that make DNA coil (spheres)

4

non-histones

proteins that control activities within segments of DNA

5

Centromere

binds chromatids together

6

Chromatid

1/2 of a chromosome that's identical (either 2 chromatids or 0 chromatids)

7

Karyotypes

a picture of all the chromosomes in a cell arranged in pairs

8

Down Syndrome

having an extra 21st chromosome due to nondisjunction
-aka trisomy 21

9

nondisjunction

centromere doesn't let go of chromosome *causing a mutation*

10

Spindle Fibers

help pull apart the cell during replication and are made up of micrtubules

11

Polar Fibers

extend across the dividing cell from centrosome to centrosome

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Kinectochore Fibers

fibers that extend from the centrosomes and begin to position them for the next phase of mitosis

13

Homologous Chromosomes

chromosome pairs - maternal with a paternal

14

Matching Homologous Chromosomes

-size
-banding pattern
-position of centromere
*Not Shape*

15

Cell Cycle

3 phases: Interphase, Mitosis, Cytokinesis

16

Interphase

(1st phase of cell cycle)
G1- cell grows, S- DNA duplicates, G2- cell prepares to divide, G0- wont divide just exits the cell cycle, R- checkpoint

17

Mitosis Phases

(2nd phase of cell cycle)
Prophase: chromosomes coil, nucleus breaks down, centrosomes move to diff. sides of cell
Metaphase: kinect. fibers move chromosomes/hold them in place
Anaphase: chromatids of each chromosome separate at centromere and move to opposite ends of dividing cell
Telophase: spindle fibers disassemble, chromosomes return to chromatin (uncoiled DNA), nucleus reforms

18

Cytokinesis

(3rd phase of cell cycle)
cell memb. divides, distributes organelles evenly near end of telophase

19

Cytokinesis in Plants

cell plate is created to be like a new cell wall which then expands into 2 new cells

20

Cytokinesis in Animals

cell pinches in creating a cleavage furrow then making 2 new cells

21

Diploid

full amount of chromosomes
2n = 46
body cells- ex: muscles, skin, bones

22

Haploid

half the number of chromosomes
n = 23
gametes- ex: egg and sperm

23

Gametes

reproductive cells, have only half the number of chromosomes as body cells

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Tetrad

paring of homologous chromosomes for crossing over

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Crossing over

the maternal/paternal chromosomes exchange DNA (genes) in prophase 1

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Meiosis Phases

Prophase 1: DNA coils, spindle fibers appear, nucleolus and nuclear memb. breaks down
Metaphase 1: tetrads line up randomly, spindle fibers attach
Anaphase 1: each homologous chromosome moves to an opposite pole of the dividing cell
Telo./Cytokinesis 1: chromosomes reach the opposite ends of cells, and Cytokinesis begins- the new cells contain a haploid number of chromosomes
Prophase 2: spindle fibers form and begin to move the chromosomes toward the midline of the dividing cell
Metaphase 2: the chromosomes move to the midline of the dividing cell
Anaphase 2: the chromatids separate and move toward opposite poles of the cell
Telo./Cytokinesis 2: a nuclear memb. forms around the chromosomes in each of the four new cells, then Cytokinesis 2 occurs resulting in 4 new cells, each of which contains half of the original cell's number of chromosomes

27

Mitosis

1 stage/4 phases
body cells (skin)
2 diploid
genetically identical (all skin cells look the same

28

Meiosis

2 stages/8 Phases
gametes
4 haploid
genetic diversity (bc of independent assortment) (crossing over in prophase 1)

29

Independent Assortment

random selection of maternal/paternal chromosomes to each pole (Metaphase 1/Anaphase 1)

30

Oogenesis

meiosis of egg cells
creates 1 viable egg + 3 unusable polar bodies

31

Spermatogenesis

meiosis of sperm cells
creates 4 viable sperm

32

DNA Replication

S Phase of Interphase (Interphase =1st phase of cell cycle)