Lecture 6: Cell Division

Front 1

Cell Genome

Back 1

all the DNA contained in a cell

Front 2

Chromosomes

Back 2

what DNA molecules are packaged into

Front 3

Chromatin

Back 3

a complex of DNA and protein that condenses during cell division

Front 4

Somatic cells

Back 4

~non-reproductive cells

~have two sets of chromosomes

~have 23 pairs of chromosomes

Front 5

Gametes

Back 5

reproductive cells; have half as many chromosomes as somatic cells

Front 6

Heterochromatin

Back 6

a less active form of chromatin

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Euchromatin

Back 7

fully active chromatin; the genes are in use

Front 8

Sister Chromatids

Back 8

two identical copies formed by the replication of a single chromosome, with both copies joined together by a common centromere

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Mitosis

Back 9

the division of the genetic material in the nucleus

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Cytokinesis

Back 10

the division of the cytoplasm

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Interphase

Back 11

~cell growth and copying of chromosomes in preparation for cell division

~about 90% of the cell cycle

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Subphases of Interphase

Back 12

~G1 phase - first gap

~S phase - synthesis; only time when chromosomes are duplicated

~G2 phase - second gap

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G2 of Interphase

Back 13

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Prometaphase

Back 14

Front 15

Prophase

Back 15

Front 16

Metaphase

Back 16

Front 17

Anaphase

Back 17

Front 18

Telophase

Back 18

Front 19

Mitotic Spindle

Back 19

is a structure made of microtubules that controls chromosome movement during mitosis

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Centrosome

Back 20

the microtubule organizing center

Front 21

Aster

Back 21

a radial array of short microtubules that extends from each centrosome

Front 22

Kinetochores

Back 22

protein complexes associated with centromeres

Front 23

Metaphase Plate

Back 23

an imaginary structure at the midway point between the spindle's two poles

Front 24

Binary Fission

Back 24

a reproductive process carried out by prokaryotes that involves chromosome replication, separation of sister chromatids, the inward pinching of the plasma membrane that results in cell division

Front 25

Origin of Replication

Back 25

where the chromosome begins to replicate in binary fission

Front 26

Cell Cycle Control

Back 26

how sequential events of the cell cycle are directed

Front 27

G0 Phase

Back 27

a non-dividing state reached in cells when there is no signal to begin mitosis

Front 28

Maturation-Promoting Factor (MPF)

Back 28

cyclin-Cdk complex that triggers a cell's passage past G2 phase

Front 29

Density-Dependent Inhibition

Back 29

an external signal where crowded cells stop dividing

Front 30

Anchorage Dependence

Back 30

Cells must be attached to a substratum in order to divide

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Transformation

Back 31

the process of a normal cell being converted into a cancerous cell

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Hypertrophy

Back 32

~Increase in cell size

~Normal organization

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Hyperplasia

Back 33

~increase in cell number

~normal organization

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Dysplasia

Back 34

~disorganized cell growth

Front 35

Neoplasia

Back 35

~disorganized cell growth

~net increase in number of dividing cells

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Metastasize

Back 36

the exporting of cancer cells to other parts of the body where they may form secondary tumors

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Genetics

Back 37

the scientific study of heredity and variation

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Heredity

Back 38

the transmission of traits from one generation to the next

Front 39

Variation

Back 39

demonstrated by the differences in appearance that offspring show from parents and siblings

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Genes

Back 40

the units of heredity, made up of segments of DNA

Front 41

Locus

Back 41

the specific location of each gene on a certain chromosome

Front 42

Asexual Reproduction

Back 42

a single individual passes genes to its offspring without the fusion of gametes

Front 43

Clones

Back 43

a group of genetically identical individuals from the same parent

Front 44

Sexual Reproduction

Back 44

two parents give rise to offspring that have unique combination of genes inherited from the two parent

Front 45

Life Cycle

Back 45

the generation-to-generation sequence of stages in the reproductive history of an organism

Front 46

Karyotype

Back 46

an ordered display of the pairs of chromosomes from a cell

Front 47

Homologous Chromosomes

Back 47

the two chromosomes in each pair

Front 48

Sex Chromosomes

Back 48

determine the sex of an individual (X and Y)

Front 49

Autosomes

Back 49

the 22 pairs of chromosomes that do not determine the sex of an individual

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Diploid cell

Back 50

has 2 sets of chromosomes

Front 51

Zygote

Back 51

a fertilized egg that has one set of chromosomes from each parent

Front 52

Meiosis

Back 52

involved in the production of one set of chromosomes; a process for only sex cells

Front 53

Meiosis I

Back 53

homologs pair up and separate, resulting in two haploid daughter cells with replicated chromosomes

Front 54

Meiosis II

Back 54

sister chromatids separate

Front 55

Prophase I

Back 55

Front 56

Metaphase I

Back 56

Front 57

Anaphase I

Back 57

Front 58

Telophase I

Back 58

Front 59

Synapsis

Back 59

homologous chromosomes loosely pair up, aligned gene by gene

Front 60

Crossing Over

Back 60

nonsister chromatids exchange DNA segments

Front 61

Chiasmata

Back 61

X-shaped regions where crossing over occurred

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Prophase II

Back 62

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Metaphase II

Back 63

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Anaphase II

Back 64

Front 65

Telophase II

Back 65

Front 66

3 Mechanisms that Contribute to Genetic Variation

Back 66

~Independent assortment of chromosomes

~Crossing over

~Random fertilization

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Independent Assortment

Back 67

each pair of chromosomes sorts maternal and paternal homologues into daughter cells independently of the other pairs

Front 68

Recombinant Chromosome

Back 68

combines the DNA inherited from each parent