Cell Cycle and Mitosis

Somatic cell

any body cell that is not involved in reproduction. Somatic cells are diploid

gamete

A sex cell (sperm or egg) that carries half the number of chromosomes. Gametes are haploid

Diploid

a cell with two sets of chromosomes - one set from each parent

Haploid

A cell with one set of chromosomes 

Homologous chromosomes

A pair of chromosomes (one from each parent) that are the same size, have the same genes in the same location, but may have different versions of those genes in the same locations, but may have different versions of those genes

Histone proteins

Proteins that DNA wraps around to help it coil, compact, and organize inside the nucleus 

Chromatin

The material is made of DNA and proteins (including histones). It can be loosely packed or tightly packed

Euchromatin

Loosely packed chromatin that is easier to access. Genes here are usually active

Heterochromatin

Tightly packed chromatin. Genes here are inactive because they are harder for the cell to access.

Sister chromatids

two identical copies of a chromosome that are formed after DNA replication and held together at the centromere

Centromere

The region where sister chromatids are attached; also the site where spindle fibers attach during cell division

karyotype

an image or chart showing all the chromosomes of an organism arranged in pairs, usually from largest to smallest 

Binary fission

a simple form of cell division used by bacteria where the DNA is copied and the cell splits into two identical cells

Cyclin

a regulatory protein that rises and falls in concentration to control progression through the cell cycle 

cell cycle checkpoint

a control point where the cell checks for problems (DNA damage, proper chromosome attachment, etc.) before moving to the next stage of the cell cycle

mitosis

The nucleus divides. Chromosomes are separated into two identical sets

cytokinesis

The cytoplasm divides, creating two separate daughter cells

What is the purpose of mitosis?

Growth, repair, and replace damaged or old cells.

What happens in prophase?

Chromosomes condense, nuclear envelope breaks down, spindle forms.

What happens in metaphase?

Chromosomes line up at center.

What happens in anaphase?

the chromosomes separate and move to opposite ends of the cell

What happens in telophase?

This forms a nuclear membrane around each new set of chromosomes.

What happens during cytokinesis?

Cytoplasm divides into two cells.

What happens at the G1 checkpoint?

Checks nutrients, DNA damage, size.

What happens at the G2 checkpoint?

Checks if DNA replicated correctly.

What happens at the M checkpoint?

Checks if chromosomes attached to spindle.

What are the three phases of interphase?

G1, S, G2.

What happens during S phase?

DNA is replicated.

What is a chromosome?

Condensed DNA ready for division.

What is uncontrolled mitosis?

Cancer

What gene prevents uncontrolled cell division?

Tumor suppressor gene (ex: p53).

mitosis vs. meiosis.

Mitosis produces two genetically identical diploid cells for growth and repair, while meiosis creates four genetically unique haploid cells, which are sex cells (gametes) for sexual reproduction

Relate DNA content to chromosomal structures.

a single chromosome is essentially a long DNA molecule tightly wound around proteins

Define chromatin and explain why it is necessary in the cell.

it packages the long DNA strands into a compact form that fits inside the nucleus and organizes the genetic material for important cellular processes like DNA replication, transcription, repair, and cell division

Identify the mechanism by which bacteria divide.

Bacteria divide through a process called binary fission, where a single parent cell replicates its DNA, grows, and then splits into two identical daughter cells

Explain the role of oncogenes and proto-oncogenes; and tumor suppressors in cell cycle control … think brakes and accelerator/gas pedal.

1. Explain the role of oncogenes and proto-oncogenes; and tumor suppressors in cell cycle control … think brakes and accelerator/gas pedal.

centriole

Cell organelle that aids in cell division in animal cells only by producing spindle fibers.

spindle fibers

Helps move chromosomes around the cell and pull apart the cell during replication and are made up of microtubules.

chromatid

one of two identical "sister" parts of a duplicated chromosome