cellular basis of inheritance

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Cellular Basis of Inheritance Chapter 9

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Cellular Basis of Inheritance. Chapter 9. Cells come from other cells. Repair Growth Reproduction Asexual Reproduction Sexual Reproduction. Sexual Reproduction. Genetic Material comes from 2 parents. Asexual Reproduction. Genetic Material comes from 1 parent Budding Cloning - PowerPoint PPT Presentation

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Page 1: Cellular Basis of Inheritance

Cellular Basis of InheritanceChapter 9

Page 2: Cellular Basis of Inheritance

Cells come from other cells• Repair• Growth• Reproduction

– Asexual Reproduction – Sexual Reproduction

Page 3: Cellular Basis of Inheritance

Sexual Reproduction• Genetic Material comes from 2 parents

Page 4: Cellular Basis of Inheritance

Asexual Reproduction• Genetic Material comes from 1 parent

– Budding– Cloning– Fragmentation– Sporulation

Page 5: Cellular Basis of Inheritance

Binary Fission (Prokaryotes way of Asexual Reproduction)• Cell division in prokaryotes produce 2

identical daughter cells

Page 6: Cellular Basis of Inheritance

The Cell Cycle• Sequence of growth

and division of a cell• Interphase = period

of growth• Mitosis = period of

nuclear division• Cytokinesis = period

of cell division

Cell Cycle Movie

Page 7: Cellular Basis of Inheritance

Limits on Cell Size• Diffusion – becomes slow and

inefficient as the cell becomes larger• Surface Area/Volume Ratio – as a cell

increases, its volume increases faster than its surface area

• DNA content – if a cell doesn’t have enough DNA to program its metabolism, it cannot survive

Page 8: Cellular Basis of Inheritance

Chromosome Structure• Chromatin -

Uncondensed form• Genetic material

spends most of its time as chromatin

• During prophase, the chromatin material coils up and condenses to become a chromosome (coiled form of DNA)

Page 9: Cellular Basis of Inheritance

Chromosome Structure

• Chromosomes -condensed rod shaped structures made of coiled DNA, (only seen in mitosis phase)

Page 10: Cellular Basis of Inheritance

Chromosome StructureThe DNA wraps around a histone core to form

bead like structures known as nucleosomes• This occurs during prophase• Histones – proteins that help DNA coil

Page 11: Cellular Basis of Inheritance

Chromosome Structure• The nucleosomes

coil even more • The coils become

the chromosome

Page 12: Cellular Basis of Inheritance

• From smallest to most coiled is the following – Double helix– DNA and histone protein– Coil– Super coil– Chromosomes

Page 13: Cellular Basis of Inheritance

Centromere• Each half of a replicated

chromosome is called a chromatid

• Sister chromatids: The 2 identical halves of the double structure are sister chromatid; exact copies of each other

• Centromere: site where sister chromatids are adjoined

Page 14: Cellular Basis of Inheritance

Chromosome or chromatid?

• 1 chromosome• 1 chromatid

• 1 chromosome (doubled)• 2 chromatids (sisterchromatids)

Replication

Page 15: Cellular Basis of Inheritance

Mitosis and MeiosisHow and Why Cells Divide

Page 16: Cellular Basis of Inheritance

Onion root

Page 17: Cellular Basis of Inheritance

Interphase• G1 phase= Growth

phase• S phase = synthesis

phase – make copy of DNA

• G2 phase – Growth and cell maintenance for preparation of division occurs: - for example copying

organelles

Page 18: Cellular Basis of Inheritance

Interphase

• Gene replication occurs

• Cell maintenance occurs:– make ATP– excrete wastes– make proteins– produce new

organelles

Page 19: Cellular Basis of Inheritance

Prophase

• Chromatin coils up into visible chromosomes

Page 20: Cellular Basis of Inheritance

Prophase

• Centrioles begin to migrate to opposite sides of the cell

• Nucleus begins to dissappear as nuclear envelope and nucleolus disintegrate

Page 21: Cellular Basis of Inheritance

Prophase

• Spindle fibers – form between centrioles

- And attach to chromosomes

Page 22: Cellular Basis of Inheritance

Metaphase

• Chromosomes line up at the center of the cell

(along the equator) • (shortest phase)

Page 23: Cellular Basis of Inheritance

Anaphase

• Chromatids split and one is pulled to each of the poles; centromere first

• Each chromatid is identical

• One copy of each chromosome goes to each side (pole)

Page 24: Cellular Basis of Inheritance

Telophase• Final phase of mitosis• Chromatids reach opposite ends

of the cell• Opposite events of prophase:

– chromosomes unwind into chromatin

– spindle breaks down– nuclear envelope forms around

2 new sets of chromosomes (to create 2 new nuclei)

– nucleolus forms in each nucleus• Cytokinesis begins (before

telophase is finished)

Page 25: Cellular Basis of Inheritance

End of Mitosis• Nuclei go back into interphase• Cytokinesis begins

Page 26: Cellular Basis of Inheritance

Cytokinesis• Animal Cells:

– Form Cleavage Furrow – membrane pinches off and

half of the cell contents go to each new daughter cell

• Plant Cells:– forms Cell Plate – because plants have a rigid

cell wall, the plasma membrane does not pinch in; a cell plate forms across the equator

Page 27: Cellular Basis of Inheritance

When do cells divide?• Growth of a multicellular organism - due to increase in # of cells, not

size of cells!– Living things grow by producing more cells, not cells getting bigger same

size now as baby, size or organism depends on number of cells– Cell division enables multicellular organisims to grow and develop from a

single fertilized egg – one single cell can divide to form a multicellular human

– Cells can grow a little bit ex fat cells don’t divide once reach puberty –but can grow much larger

• - even if not growing in size still produce new cells to replace old• Cell division even when fully grown to renew and repair cells or replace

old that die of wear and tear or accidents ex bone marrow supplys new blood cells

• *Red blood cells only live 120 days 2.5 million new must be made/second?, but must be controlled growth (or cancer)

• * Cells that line the digestive system organs – go through entire cell cycle in 6 hours