Biology 3rd test

chapters 10,11,12,13

What are sister chromosomes

2 identical copies of a single chromosome

How are sister chromosomes produced

formed during S phase of the cell cycle, cohesion holding them together.

What is the centromere

constricted region of a chromosome that serves as an assembly site for the kinetochore, ensuring that sister chromatids are correctly segregated during mitosis and meiosis

What is Kinetochore

Multi-protein complex that physically attaches the chromosome to spindle microtubules and directs chromosome movement during cell division.

Chromatid

One of two identical strands of a duplicated chromosome

Chromosome

individual complete structure of condensed DNA and histone proteins

Histone Protein

positive charged proteins that interact with negative DNA

Molecular composition of Mitotic spindle

tubulin proteins, Microtubules, Kinesin, Dynein

Function of the mitotic spindle in mitosis

Physically separate and distribute duplicated chromosomes equally into 2 identical daughter cells during mitosis.

Molecular composition of kinetochore

inner layer (DNA), outer layer (microtubule side)

Function of Kinetochore

directs chromosome movement and physically attaches chromosomes to spindle microtubules

Cellular activity in G1 phase

High metabolic activity, rapid cell growth, protein synthesis, creation of organelles.

Cellular activity G2 phase

Further cell growth, synthesis of specific proteins needed for division and duplication of centrosomes

in prophase, why does the nuclear membrane need to disappear

allows mitotic spindle microtubules physical access to chromosomes, without removal fibers can’t attach to the kinetochores

Cytokinesis

physical division of the cells cytoplasm, organelles, and plasma membrane result in one parent cell splitting into 2 distinct identical daughter cells.

When are sister chromatids separated during mitosis

Separated during anaphase, when cohesion proteins are cleaved and kinetochore microtubules are pulled toward opposite spindle poles.

Where are chromosomes found

cells of eukaryotes

nucleosomes

composed of DNA and histone proteins.

G1

primary growth phase of cell and organelle production

S (synthesis)

DNA replication copies the cell’s genome, so each chromosome has identical sister chromatids.

G2

Final growth, error proofreading, and mitosis preparation. Synthesizing structural proteins. Check and repair errors in newly replicated DNA

Mitosis

Phase in the cell cycle, in which the spindle apparatus assembles and binds to chromosomes and moves sister chromatids apart.

Prophase

Chromosome packaging and initial spindle construction

Prometaphase

Nuclear breakdown and kinetochore attachment, disintegrates nuclear membrane, extends spindle microtubules into the nuclear area to directly attach to chromosome kinetochores

Metaphase

Chromosome alignment and quality control

Anaphase

equal genetic separation, cleaves cohesion proteins and connects sister chromatids,

Telophase

Re-establishment for nuclear environments, rebuilds nuclear envelopes around 2 separate chromosome sets

Cytokinesis

phase of the cell cycle when the cytoplasm divides creating 2 daughter cells