Chapter 12 The Cell CycleA PPT by Mrs. Morton at Buffalo Acadamy of the Sacred Heart and Andrea Wise of Providence HS

Bacterial Cells

Binary Fission Circular DNA replicates Cell divides

The Cell Cycle

Interphase (90% of cycle)

• G1 phase growth • S phase synthesis of DNA

(Replication)• G2 phase preparation for

cell division Mitotic phase • Mitosis nuclear division • Cytokinesis cytoplasm

division

Cell Division: Key Roles Genome: cell’s genetic

information Somatic (body cells) cells Gametes (reproductive cells):

sperm and egg cells Chromosomes: DNA molecules Diploid (2n): 2 sets of

chromosomes Haploid (1n): 1 set of

chromosomes Chromatin: uncoiled DNA-

protein complex Chromatids: replicated strands

of a chromosome Centromere: narrowing

“waist” of sister chromatids Mitosis: nuclear division Cytokinesis: cytoplasm

division Meiosis: gamete nuclear

division

Chromosomes

Contain genetic information. Made of DNA.

Numbers of chromosomes per cell Humans--46 Total (23 from each parent) Fruit fly- 8 total Chicken--78

The # of chromosomes is not correlated with the complexity of the organism

Chromosomes

MITOSIS

DEFINITION Division of the Cell’s Nucleus

PURPOSE To ensure that each daughter cell

gets an exact copy of the chromosomes

Mitosis

Why cells must divide... List 3 reasons why cells must divide.

1 Growth of organism While each cell remains tiny

2 Repair

3 Reproduce (Mitosis-Asexual, Meiosis Sexual)

Why Cells Must Divide

Mitosis Prophase Metaphase Anaphase Telophase

Prophase Chromosomes

visible Nucleoli

disappear Sister chromatids Mitotic spindle

forms Centrioles move

to opposite poles

Metaphase Centrioles are at

opposite poles Centromeres are

aligned Kinetochores of

sister chromatids attached to microtubules (spindle)

Anaphase Paired centromeres

separate; sister chromatids liberated

Chromosomes move to opposite poles

Each pole now has a complete set of chromosomes

Telophase Daughter nuclei

form Nuclear

envelopes arise Chromatin

becomes less coiled

Two new nuclei complete mitosis

Cytokinesis

Cytoplasmic division

Animals: cleavage furrow

Plants: cell plate

Cell Cycle regulation Cell cycle

control system Checkpoints Cyclin- cell

division protein Levels of cyclins

rise and fall depending on the cycle and cellular conditions

Cell Cycle regulation Growth factors

Mitosis promoting factor (MPF)- a cyclin

Platelet Dervived GF Grow blood vessels

to new tissues Density-dependent

inhibition Anchorage

dependence

Cyclins Regulate Cell Cycle

MPF -Mitosis Promoting Factor Contains the enzyme CDK- Cyclin-

Dependent Kinase

Kinase transfers phosphate from ATP to protein (energizes a molecule needed for cell division).

Growth Factors G1 Checkpoint (G1/S): External Growth

Factors Platelet Derived GF (PDGF)- stimulates cell

division near a wound G2 Checkpoint (G2/ M)

Checks the DNA for damage

M -spindle checkpoint (before anaphase) Checks for correct mitosis and that the

spindle is correctly anchored to kinetichore

Cancer Transformation of DNA Tumor: benign or malignant Metastasis

Cancer: breast cancer cell & mammogram

Cancer NIH Animations

NIH Cancer Resources Cancer is Caused by a Combination

of Genetic Mutations Proto-oncogene- Healthy cell division

gene Becomes oncogene- mutated form

Tumor Suppressor Gene p53 is a well-known tumor suppressor gene

What phase is this?

What phase is this?

Figure 13.8a

Prophase I Metaphase I Anaphase I Telophase I andCytokinesis

Centrosome(with centriole pair)

Sisterchromatids

Chiasmata

Spindle

Homologouschromosomes

Fragmentsof nuclearenvelope

Duplicated homologouschromosomes (red and blue)pair and exchange segments;2n 6 in this example.

Centromere(with kinetochore)

Metaphaseplate

Microtubuleattached tokinetochore

Chromosomes line upby homologous pairs.

Sister chromatidsremain attached

Homologouschromosomesseparate

Each pair of homologous chromosomes separates.

Cleavagefurrow

Two haploid cells form; each chromosomestill consists of two sister chromatids.

MEIOSIS I

DRAW AND LABEL

Figure 13.8b

Prophase II Metaphase II Anaphase II Telophase II andCytokinesis

Sister chromatidsseparate

Haploid daughtercells forming

During another round of cell division, the sister chromatids finally separate;four haploid daughter cells result, containing unduplicated chromosomes.

MEIOSIS II

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Diploidgerm-linecell

Haploid gametes

Chromosomeduplication

Meiosis I

Meiosis II

HomologueHomologue

Centromere

Sisterchromatids

Synapsis:homologuescloselyassociated,and crossingover canoccur

Figure 13.9

Prophase

Duplicatedchromosome

MITOSIS

Chromosomeduplication

Parent cell

2n 6

Metaphase

AnaphaseTelophase

2n 2n

Daughter cellsof mitosis

MEIOSIS

MEIOSIS I

MEIOSIS II

Prophase I

Metaphase I

Anaphase ITelophase I

Haploidn 3

Chiasma

Chromosomeduplication Homologous

chromosome pair

Daughter cells of

meiosis I

Daughter cells of meiosis IIn n n n

SUMMARY

Property Mitosis Meiosis

DNAreplication

Number ofdivisions

Synapsis ofhomologouschromosomes

Number of daughter cellsand geneticcomposition

Role in the animal body

Occurs during interphase beforemitosis begins

One, including prophase, metaphase,anaphase, and telophase

Does not occur

Two, each diploid (2n) and geneticallyidentical to the parent cell

Enables multicellular adult to arise fromzygote; produces cells for growth, repair,and, in some species, asexual reproduction

Occurs during interphase before meiosis I begins

Two, each including prophase, metaphase, anaphase,and telophase

Occurs during prophase I along with crossing overbetween nonsister chromatids; resulting chiasmatahold pairs together due to sister chromatid cohesion

Four, each haploid (n), containing half as manychromosomes as the parent cell; genetically differentfrom the parent cell and from each other

Produces gametes; reduces number of chromosomesby half and introduces genetic variability among the gametes

PAGE256

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Fig. 12.8(TE Art)

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Metaphase I

Anaphase I

Meiosis I

Chiasmata

Mitosis

Metaphase

Anaphase

Homologues do not pair; kinetochores of sister chromatids remain separate; microtubules attach to both kinetochores on opposite sides of the centromere.

Microtubules pull sisterchromatids apart.

Chiasmata hold homologues together. The kinetochores of sister chromatids fuse and function as one. Microtubules can attach to only one side of each centromere.

Microtubules pull thehomologous chromosomes

apart, but sisterchromatids areheld together.

Fig. 12.9(TE Art)

Count cells in the zone of cell division

C C

E e

KARYTYPE

CROSSING OVER- RECOMBINATION FREQUENCY

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Yellow body color

White eye color

Vermilion eye color

Miniature wing

Rudimentary wing

y

y

w

w

v

vm

mr

r

Five characters onX chromosome

0 .01 .31 .34 .58

Wild type

Fig. 13.32(TE Art)

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Duchenne muscular dystrophyBecker muscular dystrophy

Ichthyosis, X-linkedPlacental steroid sulfatase deficiencyKallmann syndromeChondrodysplasia punctata, X-linked recessive

HypophosphatemiaAicardi syndromeHypomagnesemia, X-linkedOcular albinismRetinoschisis

Adrenal hypoplasiaGlycerol kinase deficiency

Incontinentia pigmentiWiskott-Aldrich syndromeMenkes syndrome

Charcot-Marie-Tooth neuropathyChoroideremiaCleft palate, X-linkedSpastic paraplegia, X-linked, uncomplicatedDeafness with stapes fixationPRPS-related gout

Lowe syndrome

Lesch-Nyhan syndromeHPRT-related goutHunter syndromeHemophilia BHemophilia AG6PD deficiency: favismDrug-sensitive anemiaChronic hemolytic anemiaManic-depressive illness, X-linkedColorblindness, (several forms)Dyskeratosis congenitaTKCR syndromeAdrenoleukodystrophyAdrenomyeloneuropathyEmery-Dreifuss muscular dystrophyDiabetes insipidus, renalMyotubular myopathy, X-linked

Androgen insensitivity

Chronic granulomatous diseaseRetinitis pigmentosa-3

Norrie diseaseRetinitis pigmentosa-2

Sideroblastic anemiaAarskog-Scott syndrome

PGK deficiency hemolytic anemia

Anhidrotic ectodermal dysplasia

AgammaglobulinemiaKennedy disease

Pelizaeus-Merzbacher diseaseAlport syndrome

Fabry disease

Albinism-deafness syndrome

Fragile-X syndrome

Immunodeficiency, X-linked,with hyper IgM

Lymphoproliferative syndrome

Ornithine transcarbamylase deficiency

Human X chromosome