AP Biology - Unit 4

4 types of karyotypes

* Metacentric
* Submetacentric
* Acrocentric
* Telocentric

How to differentiate karyotypes

According to the length of sister chromatids

How many somatic cells do humans have?

22 pairs

How many sex cells do humans have?

1 pair

How many chromatids in total do humans have?

46

Cell cycle

Life of a cell from its formation until it divides into 2 cells

Function of cell cycle

Reproduction, growth & tissue repair

Genome

All of a cell’s genetic info (DNA)

Prokaryote

Single, circular chromosome

Eukaryote

More than one linear chromosome

What kind of cells are created through mitosis?

Somatic cells

What kind of cells are created through meiosis?

Gametes

What are three steps of interphase?

G1, S phase, G2

G1 Phase

Cell grows & carries out normal functions

S Phase

Duplicates chromosomes (DNA replication)

G2 Phase

Prepares for cell division

4 steps of mitosis

Prophase → Metaphase → Anaphase → Telophase

Prophase

Spindle fibers become visible

Metaphase

Alignment at the equator

Anaphase

Separation of sister chromatids

Telophase

Form two identical daughter cells

Cytokinesis

* Cytoplasm divides


* Animal cells: Cleavage furrow
* Plant cells: Cell plate forms

Prometaphase

Chromosomes are lined up and each sister chromatid is attached to a spindle fiber.

How do bacterial cells divide?

Binary fission

Checkpoint

Control point where stop/go signals regulate the cell cycle

What’s the most important checkpoint?

G1 checkpoint

How is G1 checkpoint controlled?

Cell size, growth factors, env’t

What happens during G1 checkpoint “Go?”

Completes whole cell cycle

What happens during G1 checkpoint “stop?”

* Cell enters nondividing state (G0 Phase)
* Nerve, muscle cells stay at G0
* Liver cels called back from G0

How is G2 checkpoint controlled?

DNA replication completion, DNA mutations, cell size

M-spindle (Metaphase) checkpoint

Check spindle fiber (microtubule) attachment to chromosomes at kinetochores (anchor sites)

Kinases (Cdk)

Protein enzyme controls cell cycle; active when connected to cyclin

Cyclins

Proteins which attach to kinases to activate them; levels fluctuate in the cell cycle

MPF is short for?

Maturation-promoting factor

MPF function

Specific cyclin-Cdk complex which allows cells to pass G2 and go to M(mitosis) phase

Checkpoint function

Cell-cell communication to check for abnomalities

* Without this, high possibility of cancer

Growth factor

Proteins released by other cells to stimulate cell division

Density-Dependent Inhibition

Crowded cells normally stop dividing; cell-surface protein binds to adjoining cell to inhibit growth

Anchorage Dependence

Cells must be attached to another cell or ECM (extracellular matrix) to divide

Cancer

Disorder in which cells lose the ability to control growth by not responding to regulation

Transformation

Process that converts a normal cell to a cancer cell

Tumors

Mass of abnormal cells

Benign tumor

Lump of cells remain at original site

Malignant tumor

Invasive - impairs functions of 1+ organs (is cancer)

Metastasis

Cells separate from tumor & travel to other parts of body

Cancer treatment

* Surgery
* Radiation
* Chemotherapy
* Personalized medicine (ex. Breast cancer uses Herceptin to block HER2 protein)

Cancer prevention

* Don’t smoke, legal or illegal (includes hookahs, chew, 2nd-hand smoke)
* Use sun protection
* Exercise & keep weight at ideal level
* Eat 5-7 servings of fruit & veggies a day
* Use screening/preventative measures-breast/testicle/mole checks
* Practice abstinence or use condoms
* Vaccines (eg.HPV)

Characteristics of cancer cells

* Some have abnormal numbers of chromosomes
* Metabolism disabled
* Lose attachment to ECM → spread to other tissues
* Signaling molecules cause blood vessels to grow toward tumor

What phase is this?

Interphase

What phase is this?

Prophase

What phase is this?

Metaphase

What phase is this?

Anaphase

What phase is this?

Telophase

What phase is this?

Cytokinesis