Cell cycle and Cancer

Zygote

fertilized egg

Stem cells

undifferentiated cells that become differentiated into one or more types of cells

Embryonic Stem cells

Stem cells that have never been differentiated before

Adult Stem cells

They are found in adult bone marrow and can become multiple different things

examples: bone, cartilage, blood, fat, and connective tissue

Gastrula

Embryo with 3 differentiated germ layers

Organogenesis

The process of body organ and organ system formation that follows gastrulation

Cell

Most basic unit of life that has all the characteristics of life

Tissue

Group of cells working together for a common function

Organ

Set of tissues working together for a common function

Organ system

Set of organs working together for a common function

Organism

One individual member of a species

Cell Cycle

A repeated pattern of growth, DNA duplication and cell division that occurs in eukaryotic cells

- 2 purposes = growth and repair

Chromosomes

One long continuous thread of DNA that consists of thousands of genes and regulatory information

Gene

A section of DNA that contains the instructions for making a protein

Humans have how many chromosomes?

46

In normal body cells chromosomes always occur as what?

Homologous chromosomes

Chromatid

One half of a duplicated chromosome

Sister chromatids

Two identical chromatids

Centromere

Region of the condensed chromosomes that look pinched

Telomere

Ends of the DNA molecule

Interphase

The growth phase of the cell cycle

G1 phase/Gap 1 phase

Cell grows and makes protein

S/Synthesis phase

DNA replication occurs, doubling the number of chromosomes

G2/Gap 2 phase

More cell growth and protein synthesis

Mitosis

The division phase of the cell cycle

- 1 cell becomes 2 identical daughter cells

Prophase

Cromosomes condense & are visible as sister chromatids (in X's)

Nuclear membrane dissapears

Spindle fibers form out of contrioles

Metaphase

Spindle fibers connect to the centromere of each sister chromatid

Chromosomes line up in the middle of the cell

Anaphase

Sister chromatids seperate, pulling away from each other and becoming individual chromosomes

Chromatids move to opposite ends of the cell

Telophase

Chromosomes decondense and start to look like chromatin again (threadlike instead of rod like fibers)

Nuclear membrane re-forms around chromosomes at each pole

Spindle fibers break down

Cytokinesis begins

Cytokinesis

The division of the cytoplasm into 2 individual cells

Cytokinesis (in plant cells)

Cell plate forms midway between divided nuclei and gradually develops into a membrane

End result = 2 identical body cells

Cytokinesis (in animal cells)

Forms a cleavage furrow that pinches the cell into 2 equal parts

How often do cells divide?

Every cell divides at a diffrent rate based on its need

Examples: Skin cells = every 2 weeks

Red blood cells = 4 months

Why do body cells divide?

Growth and repair

Why don't body cells get bigger?

High surface area to voume ratio. This is the most effcient energy-wise and allows substances to move in and out of the cell more easily.

How is the cell cycle controlled?

A chemical control system that starts and stops the cell cycle

- proteins play a key role in this

What are the two types of cell cycle regulation?

Internal and external

External regulation + examples

Signals that come from outside of the cell

examples: Hormone, nutrients, etc.

Internal regulation + examples

Signals that come from the cell's own nucleus

examples: DNA inside of the cell

Checkpoints

Critical point where "stop" & "go" signals can regulate the cycle

Apoptosis

Programmed cell death

How is apoptosis signald? + examples

Internal and external signals that activate genes that produce self-destructive enzymes

examples: web fingers & toes during development

Cancer

Uncontrolled cell division

When does cancer occur?

When cell cycle regulation breaks down

diffrentiat between how ofter cancer cells and healthy cells divide.

Cancer cells divides more and can lead to tumors.

Tumors

Clumps of cells that divide uncontrollably

What are the two types of tumors?

Benign and malignant

Benign

Abnormal cells that typically remain clustered together

- It may be harmless & easily removed

Malignant

Cancer cells that break away from the tumor and move to other parts of the body -> more tumors

Metastasize

Spreading of disease from one organ to others

Carcinogens

Cancer causing agents

What occurs when you are exposed to carcinogens?

The chemicals cause the DNA mutation which leads to cancer

Examples of biological factors that can cause cancer.

Age, inherited genetic mutations, skin type, etc.

Examples of lifestyle choices that can cause cancer.

Diet, physical activity, exposure to UV radiation, etc.

Examples of viruses and other infection that can cause cancer.

HPV can cause cervical cancer

Other things that can cause cancer.

Tobacco smoke, abestos, etc.

Sketch a homologous chromosome pair before and after S phase?