8 Notes November 01, 2011 8 Cell... · 20/03/2017 · 8 Notes November 01, 2011 8-3 Meiosis Objectives Compare the end products of meiosis with those of mitosis. Summarize the events

8 Notes November 01, 2011

8 Cell ReproductionSection 1 ChromosomesSection 2 Cell DivisionSection 3 Meiosis

8-1 ChromosomesObjectives

Describe the structure of a chromosome.

Identify the differences in structure between prokaryotic chromosomes and eukaryotic chromosomes.

Compare the numbers of chromosomes in different species.

Explain the differences between sex chromosomes and autosomes.

Distinguish between diploid and haploid cells.

Chromosome StructureChromosomes are rod-shaped structures made of DNA and protein.

In eukaryotes, DNA wraps around proteins called histones to help maintain the compact structure of chromosomes.


Chromosome Structure

Chromosome structure, continued

Chromosomes in prokaryotes are simpler in structure than chromosomes in eukaryotes.

Chromosome Numbers

Each species has a characteristic number of chromosomes in each cell.


Number of chromosomes in various organisms

Sex Chromosomes and Autosomes

Sex chromosomes are chromosomes that determine the sex of an organism.

All of the other chromosomes in an organism are autosomes.

Chromosome numbers, continued

Diploid and Haploid Cells

Cells having two sets of chromosomes are diploid (2n).

Haploid cells (1n) have only one set of chromosomes.

Chromosome numbers, continued


8-1 Study Guide


8-2 Cell Division

Describe the events of cell division in prokaryotes.

Name the two parts of the cell that are equally divided during cell division in eukaryotes.

Summarize the events of interphase.

Describe the stages of mitosis.

Compare cytokinesis in animal cells with cytokinesis in plant cells.

Explain how cell division is controlled.

Objectives


Cell division is the process by which cells reproduce themselves.

Cell division in prokaryotes

Binary fission is the process of cell division in prokaryotes.

Cell division in prokaryotes, continued

Cell Cycle

The cell cycle is the repeating set of events in the life of a cell. The cell cycle consists of cell division and interphase.

Cell Division in Eukaryotes

Cell division in eukaryotes includes nuclear division, called mitosis, and the division of cytoplasm, called cytokinesis.


InterphaseInterphase consists of growth (G1), DNA replication, and preparation for cell division (G2).

Cell Division in Eukaryotes, continued

Stages of Mitosis

Mitosis is divided into stages: prophase, metaphase, anaphase, and telophase.

Mitosis results in two offspring cells that are genetically identical to the original cell.


Stages of Mitosis, continued

Cytokinesis

During cytokinesis in animal cells, a cleavage furrow pinches in and eventually separates the dividing cell into two cells.

In plant cells, a cell plate separates the dividing cell into two cells.

Control of Cell Division

Cell division in eukaryotes is controlled by many proteins.

Control occurs at three main checkpoints.

When Control is Lost: Cancer

Cancer may result if cells do not respond to control mechanisms.


8-2 Study Guide


8-3 MeiosisObjectives

Compare the end products of meiosis with those of mitosis.

Summarize the events of meiosis I.

Explain crossing-over and how it contributes to the production of unique individuals.

Summarize the events of meiosis II.

Compare spermatogenesis and oogenesis.

Define sexual reproduction.

Formation of Haploid Cells

Meiosis is a process of nuclear division that reduces the number of chromosomes in new cells to half the number in the original cell.

Meiosis produces haploid gametes.


Meiosis is a process of nuclear division that reduces the number of chromosomes in new cells to half the number in the original cell.

Meiosis leads to four haploid cells (gametes) rather than two diploid cells as in mitosis.

Formation of Haploid Cells, continued

Meiosis I

Meiosis I includes prophase I, metaphase I, anaphase I, and telophase I.

Crossing-over, which is when portions of homologous chromosomes exchange genetics material, occurs during prophase I and results in genetic recombination.

Meiosis I


Meiosis IIMeiosis II includes prophase II, metaphase II, anaphase II, and telophase II.

Four new haploid cells result.

Stages of Meiosis

Development of Gametes

Spermatogenesis is the process by which sperm cells are produced.

Oogenesis is the process that produces mature egg cells.


Meiosis in Male and Female Animals

Sexual Reproduction

Sexual reproduction is the formation of offspring through meiosis and the union of a sperm and an egg.

Offspring produced by sexual reproduction are genetically different from the parents.

8-3 Study Guide



Additional Instructor's Notes from previous explanations.

8 NotesCell Reproduction8-1 Chromosomes

when?histones - structure. Like a bobbin, spindle, or spool

✓

Function - non-histones


ChromatidCentromereChromatin

Dipoid Number of 2: Cell during S phase of Interphase. DNA is copied (red chromatids)

Prophase of Mitosis: Chromatin shortens, coils, and thickens. Becomes chromosomes.


MoreBetter?

Sex chromosomes

autosomes

do not confusewith sex cells.

X Y

Sex Chromosomes


homologous pairs of chromosomes

fertilization

zygoteegg

sperm

Same size, shape, and the type of information they carry

Karyotype23 pair of chromosomes in humans

1 pair-Sex Chromosomes

22 pair of autosomes

diploid

haploid

2n

1n Sex Cells

Somatic Cells

What are these numbers in Humans?

1 N = 23

2 N=46

erase below!

PaternalMaternal


8-1 Review

8-2 Cell DivisionProkaryotes

Binary fissionBacteria


Cell Cycle

m Phase

Mitosis

Meiosis

- results in 2identical nuclei.

-how sex cells aremade. 1/2 DNA (from each homologous chromosome) ends up in each nucleus

asexual

asexual

sexual-union ofGametes

-clones?Identical Genetically) offspring

Sperm egg zygote


P M A TP Prophase

MITOSIS4 phases

Metaphase

Anaphase

Telophase

AM

T


Prophase

-

1. TAKE THE FENCE DOWN (NUCLEAR MEMBRANE)2. SHORTEN, COIL AND THICKEN3. CENTROSOMES APPEAR - ANCHORS4. ROPES (SPINDLE FIBERS)KINETECHORE AND POLAR FIBERS

Metaphasechromosomes line up at mid line

AnaphaseChromatids separate

spindle fibers (kinetechore) shorten


Telophase: opposite events of prophase

Cleavage furrow

After M phase, cytokinesis follows


Mitosis

Go - cells exit cell cycle. Still alive, but do now divide anymore

Cells are idle.

Cancer- loss of control

of cell cycle.

Carcinogen - cancer causing agent

.


8-2 Review

8-3 Meiosis

Meiosis - Meiosis I

metaphase I

synapsis -homolgous chromosomes line up

tetrad - resulting shape of the four chromatids of the two homolgous pair

Crossing Over - results in increased genetic diversity


Crossing Over occurs when chromosomes that make a a tetrad exchange portions of their chromatids during synapsis. Crossing over results in an exchange of genes and in new contibinations of genes.

anaphase I

telophase I

IndependentAssortment

and Cytokinesis

Meiosis II

ChromatidsSeparate


telophase II

Cytokinesis

4 haploid offspring

spermatogenesis

Immature sperm are spermatids

oogenesis.

1 Egg (haploid)

3 Polar Bodies


each symbol represents a pair of homologous chromosomes. This cell is therefore diploid

"S" phase of interphase


The cell has just divided

anything wrong?

Telophase, followed by cytokinesis

Meiosis I

Meiosis II


8-3 Section Review


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8 Notes November 01, 2011 8 Cell... · 20/03/2017 · 8 Notes November 01, 2011 8-3 Meiosis Objectives Compare the end products of meiosis with those of mitosis. Summarize the events