BIO200 Unit 3.2

How does bacteria divide?

By binary fission (no sexual life cycle and reproduction is clonal)

How many chromosomes do humans have

46 chromosomes in 23 nearly identical pairs

How is chromatin in the nucleus organized?

It is organized into territories which contain individual chromosomes

What exists within each chromosome?

Compartment which are forms by TADs (Topologically associated domains)

Define TADs

Topologically associated domains which loops DNA in nucleosomes anchored by 2 proteins

Define Heterochromatin

DNA that is inactive and high condensed

Define Euchromatin

DNA that is active and less condensed

What are the parts of a Eukaryotic cell cycle?

Gap phase 1, synthesis, gap phase 2, mitosis, and cytokinesis

Which phase includes the gap phases 1 & 2 and synthesis?

Interphase

Which phase includes mitosis and cytokinesis?

M Phase

What are the characteristics of Gap 1?

Cells undergo major portion of growth

What are the characteristics of Synthesis?

DNA is replicated

What are the characteristics of Gap 2?

Chromosomes coil more tightly using motor proteins; centrioles replicate, tubulin synthesises

What are the five phases of mitosis?

Prophase, prometaphase, metaphase, anaphase, and telophase

What are the characteristics of Prophase?

Individual condensed chromosomes become visible as two sister chromatids, spindle apparatus assembles, and the nuclear envelope breaks down

What are the characteristics of Prometaphase?

Chromosomes begin to move to center of cell while the kinetochores of sister chromatids are attached to microtubules

What are the characteristics of Metaphase?

All chromosomes are aligned at equator of cell called the metaphase plate

What are the characteristics of Anaphase?

Cohesion proteins are removed from chromosomes, sister chromatids are degraded freeing individual chromosomes which are pulled to opposite poles and spindle pole moved apart

Which Anaphase causes the chromosomes to be pulled to opposite poles during mitosis?

Anaphase A

Which Anaphase causes the spindle poles to move apart during mitosis?

Anaphase B

What are the characteristics of Telophase?

Chromosomes are clustered at opposite poles and begin to uncoil, spindle disassembles, and nuclear envelopes re-form around chromosomes

Define Cytokinesis

The splitting of the cell into equal halves

What are the two irreversible points of the cell cycle?

Replication of genetic material and separation of sister chromatids

What is the purpose of “checkpoints” during the cell cycle?

A process where accuracy is checked and can be halted if there are errors

What are the three check points the cell cycle goes through?

G1/S, G2/M, and Late metaphase

What is the purpose of the G1/S checkpoint?

To check for damaged DNA and that all of the DNA is accounted for

What is the purpose of the G2/M checkpoint?

To make sure the cell makes a commitment to mitosis, the state of the outside environment and nutritional aspect of the cell

What is the purpose of the Late metaphase (spindle) checkpoint?

Cell ensures that all chromosomes are attached to the spindle

Define Cyclins

Proteins that change in concentration in the cell at the same time each cell cycle