Bio: U1, Ch4 - Cell Cycles

Covers U1, CH4: Prokaryote and Eukaryote review, Prokaryotic cell cyclle, mitosis, apoptosis

Prokaryotes

Single-celled organisms that lack nucleus and membrane-bound organelles

Domains under prokaryotes (2)

Bacteria, Archaea

Features of prokaryotic cells (5)

• Circular DNA (Plasmid) and chromosomes

• Ribosomes

• Cytosol

• plasma membrane

• Unicellular

Binary Fission (4)

• Prokaryotic cell replication

• asexual

• exponential (cells duplicate with each cycle)

• 2 identical copies of a cell

Steps of Binary Fission (DESC)

DNA replication

Elongation

Septum

Cell division

1. DNA replication (2)

• circular chromosome is uncoiled

• DNA and plasmids are replicated

Are plasmids always shared between cells?

nuh uhh

2. Elongation (2)

• Cell elongates to prepare for division

• duplicates migrate to opposite poles

3. Septum

• cytokinesis begins; creating septum furrow

4. Cell division (2)

• new cell wall forms in the middle of cell

• 2 NEW, IDENTICAL daughter cells created

Eukayotes

cells found in multi-cellular organisms with complex organelle structure. membrane-bound organelles, nucleus

Kingdoms under Eukarya (4)

• Animalia

• Plantae

• Fungi

• Protista

Features of Eukaryotes

• linear DNA (chromosomes)

• nucleus

• membrane and non membrane bound organelles

• body and sex cells

• meiosis and mitosis

• multicellular organisms

Membrane-bound organelles

• golgi apparatus

• mitochondria

• rough endoplasmic reticulum

• smooth endoplasmic reticulum

• lysosome

• vacuole

• nucleus → nucleolus

• chloroplast

• vesicles

Non-membrane bound organelles

• ribosomes

• centrosomes

• cytoskeleton

other cellular structures

• plasma membrane

• cytosol

• cytoskeleton

eukaryotic cell cycle

• Interphase

• mitosis

• cytokinesis

Interphase

longest part of the cell cycle; some cells stay here forever. G1, S phase, G2

Growth 1

• organelle replication

• may go into G0 or rest phase

Synthesis

• dna replication

Growth 2

• continues to replicate organelles

• protein and energy production increase to prepare for mitosis

Mitosis

cellular reproduction producing 2 identical daughter cells. PMAT.

Prophase

• nuclear membrane breaks down

• dna condenses into chromosomes

• centrosomes appear

Metaphase

• chromosomes line up in middle oif cell

• spindle fibers form and attach onto centromeres

Anaphase

• sister chromatids are pulled apart by spindle fibers towards opposite poles of the cell

• spindle fibers shorten

telophase

• cleavage furrow appears in middle of cell

• nuclear membrane begins to reform around chromosomes

• chromatids begin to uncoil

• centrosomes and spindle fibers break down

• prepares for cytrokinesis

Cytokinesis

process where a single cell divides its cytoplasm and organelles to create two new daughter cells. (mitosis/binary fission: identiucal, meiusosis: genetically varied)

Apoptosis

programmed, controlled, highly regulated cell death. can be triggered through intrinsic or extrinsic pathway. leading enzyme: caspases

Necrosis

premature cell death caused by damage, infection or disease.

Intrinsic Pathway

• mitochondrial

• mitochondria receptors receive signal to begin apoptosis

• mitochondrial membrane becomes more permeable to release proteins into cytoplasm

• proteins trigger release of caspases

Extrinsic Pathway

• Death receptor pathway

• death receptors on plasma membrane receive signal from molecule binding to staret apoptosis

• activates caspases

Caspases

enzyme that chops up cellular organelles, DNA, cytoskeleton etc

Steps in apoptosis

• intrinsic/extrinsic athway

• caspases do theur worekj

• cell contents are broken down

• cell blebs; fragments of cell content enclosed in vesicies

• vesicles are digested by endocytes

Importance of Apoptosis

1. Health and maintenance

2. Development

Apoptosis in Health

• eradicates damaged cells and cells with mutations and damaged DNA

• prevents cancer and cancerous growths

Apoptosis in Development

• “carves out” shapes from when organisms grow

Apoptosis Checkpoints

G1, G2, M