BIOLOGY 1Cell Cycle

Cell Review

Cell Theory:* All living things composed of cells* Cells are the basic units of structure and function in living things.

* New cells are produced from existing cells

Cell ReviewNucleus of the Cell:

Controls most cell processes and contains the hereditary information. This is found as Deoxyribonucleic Acid (DNA)

Chromatin: DNA bound to protein – granular and visible in the nucleus.Chromosomes: Chromatin that condenses in preparation for cell division.

DNA: Coded instructions for making proteins.

Cell ReviewMicrotubules: They aide in cell division, separating

chromosomes (known as centrioles in animal cells).

Cell DivisionPROKARYOTE CELL DIVISION EUKARYOTE CELL DIVISION

Asexual Reproduction Growth and replacement of old and/or dying cells

DNA = One Circular Chromosome and Plasmids

DNA = 10-50 chromosomes per cell Humans = 46 (23 identical pairs)

Cell Division called the Cell CycleCell Division called Binary Fission

Cell ReplicationCell Cycle:

Phase 1: Interphase

Phase 2: Mitosis

Phase 3: Cytokinesis

G1 - primary growth phaseS – synthesis; DNA replicatedG2 - secondary growth phase

Cell Replication (Cell Cycle)

Phase 1: InterphaseG1 - primary growth phase

S – synthesis; DNA replicated

G2 - secondary growth phase

Cell Matures: Growth and Organelles

DNA copied/replicated

Cell Structures needed for division made Centrioles

Mitosis: Prophase Chromatin condenses into chromosomes Mitotic spindle forms and attaches to

centromeres Nuclear membrane/nucleolus broken

down.

Mitosis: Prophase

dissolving

Centrioles

Mitosis: Metaphase Chromosomes line up at the equator of

the cell

Mitosis: MetaphaseCentriole

Centriole

CentromereEquator

Mitosis: Anaphase Sister Chromatids pulled apart to

opposite poles of the cell.

Anaphase

Equator

Review

Mitosis: Telophase Sister Chromatids completely at opposite

poles Nuclear envelope forms Nucleolus appears Cytokinesis occurs

Mitosis: Telophase

Equator

Cell Replication (Cell Cycle)Phase 3: Cytokinesis

Division of cell into two – Division of the cytoplasm by a

cleavage furrow

Cleavage Furrow

Cell Cycle Drawing

• Interphase• Nuclear Membrane• Chromatin

• Prophase• Centrioles• Nuclear Membrane (disappearing)• Chromosomes

• Metaphase• Centrioles• Chromosomes• Mitotic spindle

• Anaphase

• Centrioles• Chromosomes• Mitotic spindle

• Telophase/Cytokinesis• Chromosomes returning to chromatin• Nuclear Envelope

forming• Cleavage Furrow

Draw and Label the Following:

19

What Phase?

20

What phase?

21

Name the Stages of Mitosis:

Interphase

Early prophase

Mid-ProphaseLate Prophase

Metaphase

Late Anaphase

Early Anaphase

Early Telophase, Begin cytokinesis

Late telophase, Advanced cytokinesis

http://www.youtube.com/watch?v=ZEwddr9ho-4&feature=related

23

Cell ChromosomesKaryotype A picture of the

chromosomes from a human cell arranged in pairs by size

First 22 pairs are called autosomes

Last pair are the sex chromosomes

XX female or XY male

24

Boy or Girl?

Y - Chromosome

X - Chromosome

The Y Chromosome Decides

Meiosis – Formation of Gametes(Eggs and Sperm)

Spermatogenesis (formation of sperm)Females:Males:

Oogenesis (formation of eggs)

Two Stages: Meiosis I and Meiosis IIDuring Meiosis I – Homologs form Tetrads and crossing over occurs, all resulting cells are still diploid (2N) 46 chromosomes

During Meiosis II – Chromosomes are split and all cells become haploid (1N) 23 chromosomes

Why is this important?Entire process called reduction division

26

Homologs form Tetrads Homologous chromosomes(compare to sister chromatids)  

Join to form a tetrad

Called Synapsis (compare to a centromere)

27

Crossing-Over Homologous

chromosomes in a tetrad cross over each other

Pieces of chromosomes or genes are exchanged

Produces Genetic recombination in the offspring

28

Crossing-over multiplies the already huge number of different gamete types

Crossing-Over

Cell Cycle and Meiosis

Lets compare Mitosis and Meiosis –

What do you know?

46 chromatids(92 chromosomes,

paired after replication – held by a synapsis/centromere)

46 chromosomes each side

Mitosis: 46

chromosomesMeiosis: 23

chromosomes

31

Mitosis MeiosisNumber of

divisions 1 2

Number of daughter cells 2 4

Genetically identical? Yes No

Chromosome # Same as parent Half of parent

Where Somatic cells Germ cells

When Throughout life

At sexual maturity

Role Growth and repair

Sexual reproduction

Comparison of Divisions