CELL DIVISIONMITOSIS AND

MEIOSIS

_____ overload (information crisis)Surface area to volume ratio (_____ increases

MUCH faster than surface area.)A cell’s s.a. cannot increase fast enough to

meet the demands of the internal volume of the cell. In other words, it will not be able to bring in _____ and get rid of ______ fast enough for the cell to survive.

LIMITS TO CELL GROWTH

_____ within a cell can only diffuse so far no matter how big the cell gets.

For example, if a cell’s volume becomes too great, CO2 will never be able to diffuse out of a cell, thereby killing the cell.

Cells need a large s.a. to take in _____ and excrete _____.

LIMITS TO CELL GROWTH

LIMITS TO CELL GROWTH

Red blood cells have a biconcave surface which increases their surface area making them more efficient at what they do best – exchange gases.

Some review:Not all cells are alike.  Even cells within the same organism show enormous diversity in size, shape, and internal organization.  Your body contains over _____ different cell types.

Remember, cell _____ fits cell _____!What are stem cells? Let’s see…

The Nature of Stem Cells What are stem cells? (4:10)

CELL DIFFERENTIATION AND STEM CELLS

Binary fi ssion The cell simply

copies its _____ info, separates that info, then splits in half – no distinct _____ occur.

Binary fission (:41) Another one (1:03)

PROKARYOTIC CELL DIVISION

Chromosomes Made of _____ and

_____ Each species has its

own specific number of them. (We have _____ per cell.)

CELL DIVISION

What is a chromosome?

G0 phase – occurs in _____ cells (like brain cells) or in cells that no longer will _____ Most cells stop dividing after about _____ divisions.

G1 phase – cell _____ and produces new _____ and _____. The “no turning back” phase (restriction point)

S phase – chromosomes are _____ and DNA is _____

G2 phase – _____ and molecules needed for _____ are produced

CELL CYCLE – INTERPHASE

Interphase (3:45)

CELL CYCLE – INTERPHASE

Ninety percent or more of the cell cycle is spent in interphase.

Chromatin _____._____ migrate to opposite poles (centrosome)._____ fibers form._____ _____ broken down by enzymes.Nucleus _____.Longest phase of mitosis

CELL CYCLE – PROPHASE

CELL CYCLE – PROPHASE

_____ line up across the equatorial plate._____ _____ attach to kinetochores on

chromatids.

CELL CYCLE – METAPHASE

_____ separated by spindle and pulled to opposite _____ of the cell.

Shortest phase of mitosis

CELL CYCLE – ANAPHASE

New _____ _____ form around chromosomes._____ uncoil and disperse within envelope.New _____ form in each cell.

CELL CYCLE – TELOPHASE

Division of the _____ down the middle of the two new cells.

Plant cells form a _____ _____ which will become the cell _____.

Begins during anaphase once the _____ separate.

CYTOKINESIS

REVIEW OF CELL CYCLE

Another video (1:00)

Mitosis video (1:30)

Some white blood cells, epithelial cells of small intestine – 1 day or less

Red blood cells – 120 daysNeurons, stem cells, kidney cells, eye cells,

some immune cells – lifetimeThe point is, all cells have a _____ which varies

from one cell type to another. What is apoptosis? (_____ _____ _____)About 50-70 billion cells undergo apoptosis dailyApoptosis video (2:55)Another one (1:33)

CELL LIFESPAN

Normally, cells will stop dividing when they _____ each other.

Cells will divide rapidly at sites of _____ (skin cells at a cut for example).

Cyclins – A group of _____ that regulate the _____ _____ (CA, CB,

CD, CE) Different cyclins are _____ at different times in the cell

cycle.Regulators –

A group of proteins that respond to events inside (_____ regulators) and outside (_____ regulators) the cell

REGULATING THE CELL CYCLE

Occurs when cells lose their ability to control their _____. (They don’t respond to _____.)

Many _____ (more than 50%) have a defect in the regulator p53 (p=protein; 53=molecular mass)

p53 was awarded Molecule of the Year in 1998. What an honor!

p53 (1) activates DNA repair proteins; (2) halts the _____ _____ when necessary; (3) initiates _____; and (4) prevents _____ (blood vessel formation)

When the gene that controls p53 is damaged, _____ often form.

CANCER

Diff erences between benign/malignant/metastatic tumors

What are carcinogens?Cancer explanation (3:50)

What are oncoviruses?

CANCER

Cancer Overview (4:30)

Homologous chromosomes Chromosomes that

contain the same _____ (example: We get one chromo with the eye color gene on it from _____ and one from _____.)

They don’t have identical genes on them; rather, the genes control the same _____.

Meiosis video (2:58)

MEIOSIS

Diploid/Haploid Terms used to describe cells in terms of their

number of _____ Somatic cells – _____ (46) Gametes – _____ (23)

Meiosis is a form of reduction division. It only occurs in the _____ (sperm and egg cells).

There are two distinct divisions – meiosis I and meiosis II

Both divisions are pretty much the same as _____ except prophase I.

MEIOSIS

Prophase I begins with homologous _____ pairing up to form a _____ (four chromatids). Crossing-over occurs during this phase.

Exchange of _____ takes place between homologous chromosomes leading to greater _____ _____.

MEIOSIS

Progression of meiosis in humans: One cell with _____ chromatids in prophase I two

cells with _____ chromatids in prophase II four cells with _____ chromosomes

The final result is four _____ different _____ cells.

MEIOSIS

MEIOSIS

Crossing Over (:43)

Meiosis Video (3:03)

MEIOSIS QUIZ

Division of prokaryotes is called . . .

The four phases of mitosis in order . . .

Volume or surface area grows faster?

# of chromosomes in human somatic cell?

REVIEW TIME!

Two sista ___________ make up a chromosome.

Structures that pull apart chromosomes . . .

The “no turning back phase” . . .

# of chromosomes in human sex cell (gamete)?

REVIEW TIME!

New nuclei form in each daughter cell during . . .

Chromatin condenses during . . .

Chromosomes separated during . . .

REVIEW TIME!

Organelles that produce spindle fibers . . .

Dormant cells are in the _____ phase.

Interphase is subdivided into _______, _______, and _______.

REVIEW TIME!

Chromosomes line up along equatorial plate during?

Nucleus dissolves during . . .

Division of cytoplasm is called . . .

REVIEW TIME!

Describe differences between benign, malignant, and metastatic tumors.

The four main functions of p53 are . . .

Anything that is capable of mutating DNA and causing cancer is a _____.

What is an oncovirus?

REVIEW TIME!

Chromosomes that contain genes that control the same traits are called _____ chromosomes.

What important event occurs during prophase I of meiosis?

Why is this event important?

REVIEW TIME!