Topic 8 Cell Cycle & DNA Replication Review

make sure you put "answer with definition"

purpose of cell division?

growth, repair, and reproduction.

interphase

longest phase of the cell cycle, consisting of three stages: G1, S, and G2

G1 - Cell increases in size, preparation for DNA replication, and new organelles/proteins are made

What is G0

Cells exit the active cell cycle and temporarily stop dividing/cells that don’t do mitosis (nerve cells)

S - the cell duplicates its entire genome, ensuring that each daughter cell receives an identical copy of the genetic material.

G2 - Growth and prep for mitosis. Organelles replicated (especially centrioles in animal cells)

Cyclins

A protein manages cell cycle checkpoints

Prophase - Chromatin condenses into chromosomes, spindle fibers form and attach to centromeres, centrioles move to opposite poles, nuclear envelope disappears

Metaphase - chromosomes are moved to metaphase plate. Checkpoint: are spindles attached to all centromeres.

Anaphase - spindles pull sister chromatids to opposite poles and cell becomes longer

Telophase - spindle breaks down, cytoplasm cleaves (cleavage furrow), nuclear membrane reforms, chromosomes decondense into chromatin

cytokinesis phase

Division of cytoplasm and cell membrane resulting in two daughter cells. Animal cells, a cleavage furrow forms and pinches the cell into two. Plant cells, a cell plate forms between the daughter nuclei and develops into a new cell wall.

purpose of mitosis

Repair tissue, replace cells, growth, asexual reproduction

chromatin

A mixture of DNA and proteins will form the chromosomes during mitosis

chromosomes

Chromatin that is condensed intro structures to be used during cell division

chromatid

One of two identical halves of a chromosome; sister chromatids are identical

sister chromatids

Identical copies of a chromosome, connected by a centromere.

centromere

Region where sister chromatids are joined.

centriole

Organelle involved in spindle fiber formation.

Spindle fibers

Microtubules that separate sister chromatids during cell division.

Mitotic Index (not formula)

Measure of the percentage of cells in a population undergoing mitosis

formula for mitotic index

(number of cells/total number of cells)100

cancer

Abnormal/uncontrolled cell growth

characteristics of cancer cells

Grow uncontrollably, invade nearby tissues, and spread to other parts of the body. They ignore signals that regulate normal cell division and often carry genetic mutations.

P53 gene

Tumor suppressor gene involved in regulating cell division and preventing mutations.

tumor

Abnormal mass of cells.

contact inhibition

Normal cells stop dividing when they come into contact with other cells, but cancer cells continue to divide uncontrollably.

DNA

Genetic information in all living organisms

structure of DNA

Double helix composed of nucleotides.

base pairing of DNA

Adenine (A) pairs with Thymine (T), and Cytosine (C) pairs with Guanine (G)

antiparallel

The two strands of DNA run in opposite directions.

nucleotide structure

Phosphate group, a sugar molecule (deoxyribose 5’ and 3’), and a nitrogenous base.

DNA replication

Process by which a cell makes an identical copy of its DNA (S phase, nucleus)

exanucleases

Removes mismatched DNA nucleotides replaces w/ correct ones

DNA helicase

Unwinds DNA by breaking H-bonds making replication fork

topoisomerase

Relieves tension from helicase by preventing super-coiling

single stranded binding proteins (ssbp)

Prevents DNA from reforming after H bonds are broken by helicase

DNA primase

Builds short sequence of RNA primer on parent strand for DNA polymerase III to bond

DNA polymerase III

Adds new DNA nucleotides in 5’ to 3’ direction

nucleoside triphosphates

Nucleotide w/3 phosphastes to provide energy to DNA poly III

leading strand

New strand built continuously toward replication fork

lagging strand

New strand built discontinuously in fragments away from replication fork

DNA polymerase I

Replaces the RNA primer w/DNA nucleotides (one on leading, multiple on lagging)

DNA ligase

Joins sections of DNA (Okazaki fragments) by forming phosphodiester bonds.

direction of DNA synthesis

5’ to 3’ direction

where does DNA polymerase attach

Attaches to the 3’ end of the primer

Why does DNA elongate in the 5’-->3’ direction?

Due to the structure of the DNA molecule and the directionality of DNA polymerase.

okazaki fragments

Short segments of DNA that are synthesized discontinuously on the lagging strand during DNA replication.