lecture 8 - Cell division and cell cyle

Describe briefly cell division?

• Cells duplicate genetic material before they double

• Ensures each daughter cell has same DNA

Describe cells in animals?

• somatic cells have 2 sets of chromosomes

• One from each parent,

Describe prokaryotic cell division?

• Binary fission - asexual reproduction where a cell expands and divides in two

Describe eukaryotic cell division?

• Interphase - cell grows, chromosomes are duplicated with same DNA

• Mitosis - chromosomes are copied and separated, each end of cell

• Cytokinesis - cell divides into two daughter cells, identical to each other

Describe chromosomes, chromatids and centromeres

• Unduplicated chromosomes has two chromosome arms

• Duplicated chromosomes have two sister chromatids

• Once sister chromatids separate, they become their own unduplicated chromosome

Describe the process of cell division?

• Interphase - G1, S, G2

• G1 - normal cell metabolism

• S - DNA replication

• G2 - checking DNA replication before cell division

• Mitosis - replicated chromosomes seperate

• Cytokinesis - physical cell division

Stages of Mitosis?

• PPMATC

• Prophase

• Prometaphase

• Metaphase

• Anaphase

• Telophase

• Cytokinesis

Describe Prophase?

• DNA condense from chromatin into x shaped duplicated chromosomes One

• Centrosomes divided as well as microtubules form mitotic spindles

Describe prometaphase?

• Nuclear membrane breaks down

• Chromosomes are connected to microtubules via kinetochores

Describe metaphase?

• Mitotic spindles move chromosomes to middle of cell

Describe anaphase?

• Microtubules pull sister chromatids apart

• Chromatids are pulled to opposite ends of cell (as microtubules get shorter)

Describe telophase?

• Two sets of chromosomes seperate are used to create new nucleus

• Cells split into 2 via cytokinesis

Describe cytokinesis?

• Pinching action separates cytoplasm into 2 seperate cells

• Animals - from a cleavage

• Plant cells - form a cell plate

Describe the cell cycle control system?

• G1 - does the cell need to reproduce again

• G2 - is the DNA damaged, ready to go

• M - Are chromosomes split correctly

Describe defects in the cell cycle?

• Uncontrolled cell division can lead to cancer

• Genes become oncogenes and cause DNA mutation