Cell Growth & Division

Binary fision

Cell division in prokaryotic cells where DNA is copied through DNA replication. The DNA copies and cytoplasm of the cell are divided equally.

Chromatin

DNA in a loose, uncoiled state; consists of DNA and proteins

Chromosome

A structure of highly condensed and coiled DNA, allowing for easing dividing during mitosis

Interphase

Non-dividing stage of a cells life, consists of growth, DNA replication, and other steps to prepare for cell division (G1, S, G2)

Mitosis

Division of the nucleus and genetic material; has 4 phases - prophase, metaphase, anaphase, and telophase. Purpose is to divide doubled DNA evenly, creating two new genetically identical nuclei.

Cytokinesis

Division of the cytoplasm and organelles occurring after mitosis. Creates two genetically identical daughter cells.

Diploid (2n)

Cell made up of 2 copies of every chromosome (a full set of genetic material. In humans 2n = 46

Haploid (n)

Cell made up of 1 copy of every chromosome (a half set of genetic material. In humans n = 23

Gamete

Sex cell (egg or sperm), are haploid, containing half of the genetic material, formed by meiosis

Somatic cell

Body cell (ex: skin cell, brain cells), are diploid, containing the full amount of genetic material, formed by mitosis

Zygote

Fertilized egg (diploid), 1st cell of an offspring that results from the fusion of two haploid gametes

Meiosis

Division of the nucleus and genetic material in order to make haploid gametes, consists of 2 rounds of PMAT. After cytokinesis, results in 4 genetically different haploid daughter cells.

Sister chromatids

Identical copies of chromosomes that results from DNA replication, joined together by a centromere.

Karyotype

Organized image of homologous chromosomes of an individual. Can be used to determine if piece or entire chromosomes are missing or duplicated.

Location of the cell cycle checkpoints

G1, M, and G2

Tumor suppressor gene

Genes that code for proteins that discourage progression through the cell cycle, aka the “breaks” at each checkpoint

Proto-oncogene

Genes that code for proteins that encourage progression through the cell cycle, aka the “gas pedals” at each checkpoint

DNA is inaccessible when it is ___

tightly coiled

DNA is accessible when it is ___

loosely coiled, chromatin

Direction of enzyme movement

3’ to 5’ (sweet tooth)

Helicase function

Unzips DNA by breaking the hydrogen bonds between bases

DNA polymerase function

Adds complimentary nucleotides to the correct bases on the original DNA strands and connects them

DNA ligase function

Fills in the gaps between the okazaki fragments in the lagging strand

G1 key process

Cell increases in size, organelles duplicate at end

Synthesis key process

Duplicate DNA

G2 key process

Check for DNA errors + repairs them, cytoplasm completely divided

Mitosis key process

Cell and nuclear splitting

G0 key process

Cell “at rest” doing its job (differentiated cells)

Mnemonic for prophase

Prepare; for cytokenesis

Mnemonic for metaphase

Move to middle

Mnemonic for anaphase

Away or apart

Mnemonic for telophase

Two nuclei

Purpose of cell cycle checkpoints

Making sure everything in the cell is working properly before dividing

Term for cell death

Apoptosis

What a typical tumor “looks” like

Lots of irregularly shaped cells with more nuclei and cytoplasm

Benign

Cancer cells stay at original site

Malignant

Cancer cells spread to other parts of the body through metastasis

Metastasis

The process that allows cancer cells to spread to other parts of the body

BRCA-1

Breast cancer susceptibility gene 1, a tumor suppressor gene

Carcinogens

Substances that promote formation of cancerous cells, accelerates cell division, and tricks cell cycle to continue

Mutagens

Directly damages DNA, can lead to cancer

Carcinogen examples

Cigarettes or preservatives

Mutagens examples

UV or drugs

Chemotherapy

Drugs that kill all fast growing cells

Radiation

High energy rays (ex: gamma rays) to destroy tumor

Surgery

Cut out tumor

Are chromosomes visible during interphase?

No

Are chromosomes visible during mitosis?

Yes

Autosomes

Chromosomes #1-22

Sex chromosomes

Chromosomes X and Y

Oocytes

Make 4 egg cells with oogensis

Spermatocytes

Make 4 sperm with spermatogenesis

Oogenesis

Meiosis for egg cells

Spermatogenesis

Meiosis for sperm cells

Crossing over

Homologous chromosomes “swap” their genes

Independent assortment/orientation

Different combinations of chromosomes inherited by egg and sperm cells pair up randomly during metaphase 1

Importance of genetic diversity

To survive (ex: diseases)

Fertilization

One unique sperm will fertilize a unique egg, forming a zygote

Mitotic Index

The ratio of cells undergoing mitosis to the total number of cells in a population