Bio Exam #2

Interphase

The preparatory phases of the cell cycle. The cell makes a copy of the DNA and produces more organelles and cytoplasm.

S Phase

DNA replication occurs. Each chromosome is replicated to produce two identical sister chromatids.

G1 Phase

The cell enlarges, creates additional cytoplasm, and begins to produce new organelles.

G2 Phase

The final preparatory stage, during which the cell prepares for division.

Mitosis

The sister chromatids of each chromosome separate from each other, setting up the two identical nuclei of daughter cells.

Cytokinesis

Daughter cells physically separate from each other.

Uncondensed DNA - Chromatin

In nucleus of cell in G1.

Chromosomes

Before replication, DNA condenses into this. See this in the nucleus before the cell starts. S of interphase.

DNA Replication Purpose

To copy original DNA strand into 2 strands of (DNA identical to original)

DNA Replication Occurs

During S of Interphase in the cell cycle

DNA Helicase

Hydrogen bonds separate with this

DNA Polymerase

Adds bases to the now single strands of DNA

Covalent Bonds

Between sugars and phosphates of nucleotides occur to make backbone of new strands.

Semiconservative

Each new DNA molecule is half new and half old

DNA Replication results

Results in two identical DNA Molecules

Centromere

Two sister chromatids are connected by this

Double Check

Occurs after G2 of interphase in preparation for mitosis

Mitosis Purpose

Separates sister chromatids so that each new cell will have a complete set of chromosomes

Happens in somatic cells → body cells

G1 checkpoint

Involves genes that make proteins that STIMULATE cell division

G2 Checkpoint

Involves genes that make proteins that check DNA and INHIBT cell division if DNA is too mutated

Encourages Cell Division in G1 Checkpoint

• Presence of Growth Factor(s)= Signal to divide

• Enough nutrients & energy

• Cell is large/mature enough

Proto- oncogenes

• G1 checkpoint

• code for some growth factors or their receptors that regulate cell divisions

• proteins are made by this

• Cells only divide when necessary - they are stimulated to do so

Tumor suppressing Proteins

• G2 checkpoint

• Check DNA for errors

• Fix DNA

• Halt division (via apoptosis) if major issue exists

• (p53 is a one)

Cancer

• Increased cell division

• Cell pile up

• Invasion of nearby tissues

• Nutrients available for growth due to new blood vessels growing towards cell

• Cells can travel through the body

• Immortality - don’t have a timeline

• Caused due to accumulation of mutations

Oncogenes

mutated proto-oncogenes

• motivate cell to keep dividing w/o stimulation

Tumor suppressor mutated

• cell can override checkpoints

• DNA not checked or repaired, nor will cell cause apoptosis

• Mutations passed to daughter cells

Contact Inhibition in Normal Cell

• Send out chemical message to prevent other cells from growing on them

• Transforming Growth Factor Beta present

• mature and play non-contact sport

Contact Inhibition in Cancer cells

• Cell ignores message

• Cell ‘piles up’ on each other

• immature and football team

Angiogenesis

the form of new blood vessels

• Cells have this for emergencies

Angiogenic Proteins

• Released by cancer cells

• Source of nutrition & O2 for tumor growth

• Extra growth diverts nutrients & O2 form healthy cells

Anchorage Dependence in Normal Cells

• Proteins for inter cellular space binding substrate keep cells in correct area

• Protein sends continual signals to nucleus that cell is in correct area

• Cell doesn’t receive message apoptosis will occur

Apoptosis

• Self destruct button

• Programmed cell death

Anchorage Dependence in Cancer cells

• A mutated gene sends protein signal that cell is bound when it is not

• Apoptosis doesn’t occur

• Metastasize

Metastasize

Cells ability to travel is other parts of the body

Cell Death in Normal Cells

• “cellular clock” determines how long a normal cell will live

• Telomeres

Telomeres

protective caps on chromosomes that wear down during cell division

• cell dies after caps wear off

• Plastic cap on shoelace

• Some cells have longer caps than others

Cell Death in Cancer cells

• Immortal

• Mutation causes telomerase gene to turn on

• telomerase remains long and cell never dies

Telomerase

enzyme that maintains & rebuilds telomeres

Dysplasia

Changes for worse in cell structure — cell may becoming pre-cancerous

• Large nuclei

• Many dividing cells waste of space and resources

• Variation of size and shape

• Loss of normal features

These trigger cancer mutations

1. Organic Chemicals - smoking cannabis

2. Radiation- UV and Radon gas

3. Viruses- Hep B and HPV

Ways to prevent cancer

• Avoid Obesity

• Lower Saturated Fats

• Eat High fiber foods

• Look for anti-oxidant

• Avoid smoking alcohol or nitrite based food

Surgery

Get ride of as many cells as possible

Radiation

Carcinagen - has to belocalized kills all living cells - paired with surgery

Chemotherapy

Target certain areas & go after cells that are rapidly growing

Bone Marrow Transplant

Take out WB cells then put them back in

Targeted Therapies

Blocks the growth of cancer cells by interfering with gene non-cancer cells that don’t have gene don’t get deleted

Immunotherapies

Stimulate immune system to fight cancer

Antihoromone Therapy

Breast & Reproduction reduce hormone to stop cancer

Gene Therapy

CRISPR- Give cells that work to people who need

Homologues Chromosomes

Term used to refer to chromosomes that each have a corresponding chromosome from the opposite- sex parent, each chromosome in a pair are from a different parent but for the same kind of gene

Non-Homologues Chromosomes

Chromosomes that don’t share same characteristics within cell

Gametes have

½ genetic material of a somatic cell

Somatic

2-2n cells that are exact replica of first cell

Gametes

• Start with 2n cells end with 4 haploid cells

Homologous Pair of Sister Chromatids

Duplicate & still connected

Meiosis 1

• Homologous chromosomes separate, halving the chromosome number

• Crossing over occurs

• Sister chromatids here

• Homologous pairs detach

Meiosis 2

• Chromatids line up in middle and realign again

• Separate into 4 haploid cells

Recombination/Crossing Over

• The act of Homologues Chromosomes. Mom and Dad switching a part of chromatid for genetic diversity

• How Meiosis creates genetically diverse Daughter cells

Random Alignment

• When Homologues sister chromatids line up they line up in random order

• This allows for genetic diversity through the random and not uniform alignment

Cancer

A disease caused by various mutations and often involves tumors caused by abnormal and uncontrolled cell division.

Chemotherapy

A class of drug used to treat cancer.

Interphase

A section of the cell cycle. Interphase G1, S and G2.

Mitosis

A part of the cell cycle that involves dividing already duplicated chromosomes into 2 new daughter cells that are genetically the SAME as the parent cell (which means they are 2n diploid cells as well). Involved with asexual reproduction

Sister Chromatids

Identical copies of a chromosome bound together by the centromere

Mutation

Something that will cause a cell to have cancer or a anormal trait

Cell Cycle Checkpoints

Happen at G1 (involves proto-oncogenes) and the a REASON to divide and G2 (tumor suppressors) which can INHIBIT cell division if replicated DNA is has too many errors when checked

Apoptosis

programmed cell death - result of there no longer being a chemical message being sent to the nucleus that the cell is in the correct spot. (Why would a cell self-destruct?)

Tumor

mass of rapidly dividing cells that can damage surrounding tissue. Do you know the mutations that can cause a mass of cells?

Radiation Therapy

Treatment of cancer with a radioactive substance, x-ray, or radiation, radiation is applied to isolated areas of the body to target remaining cancer cells. What is a characteristic of a cancer cell that would make radiation necessary?

Metastasis

The spread of cancer cells beyond their original site. Involves mutated anchorage dependence.

Carcinogen Mutagens

Environmental agent that promotes cancer (ex. Viruses, chemicals, radiation)

Proto-oncogenes

DNA codes for proteins that stimulate normal cell growth and division. They make Growth Factors and their receptors.

Growth Factors

Regulatory Proteins (such as hormones) that tell the cell there is a reason to divide. They are basically regulatory proteins that ensure that the events of cell division occur in the proper sequence and at the correct rate/time. They are made by proto-oncogenes and are involved with the G1 checkpoint.

Receptors

Proteins on the cell membrane that receive growth factors to create a message to the nuclei about what is going in. They are made by proto-oncogenes

Tumor suppressor genes

Genes that regulate the cell cycle by INHIBITING it if there are errors (mutations) in the replicated DNA. They double check the newly replicated DNA by flagging mutations, fixing those mutations, or causing apoptosis if there are too many mutations — thereby preventing the uncontrolled cell growth hat contributes to cancer. They do their job in G2 and are involved with the G2 checkpoint.

Oncogene

Cancer-causing genes that are formed due to mutations, They can cause mutations to growth factors and their receptors so that cells think there is a reason to divide when there is not. They cause problems in the G1 checkpoint. They are the mutated form of an oncogene

Benign Tumor

A mass of abnormal ce3lls that remains at the site of origin (non cancerous). Do you remember the characteristics of them and what mutation can cause these?

Malignant Tumor

A cancerous tumor that is invasive enough to impair the functions of one or more organs, and could metastasize. Do you remember the characteristics of them and what mutations can cause these characteristics?

Contact Inhibition

A process that stops additional cell growth when cells become crowded. Prevents cells from piling up o each other and involves TGF-Beta.

Angiogenic Proteins

Angiogenic are the proteins that build the blood vessels and attach them to the area of the body that sent a request

Anchorage dependence

Keeps specialized cells in their correct area so they don’t break free and grow in areas they don’t belong. Involves a substrate protein binding and if a cell detaches from this binding it will self destruct (apoptosis)

Binding substrate

protein binding that sends a message to nucleus that the cell is in the correct spot

Lymphatic system

Composed of a network of vessels, ducts, nodes, and organs. Provides defense against infection. Lymph nodes can be tested to find traces of cancer cells

Cell Death

What’s an example of cell death? happens because cell is no longer being needed, a signal the cell isn’t in the right location, a badly mutated cell, no longer carrying out its function.

Telomeres

DNA that are at the tips of chromosomes, caps for the cell, they degrade with each replication until they disappear-which means it’s time for the cell to die.

Telomerase

An enzyme that catalyzes the lengthening of telomeres in eukaryotic germ cells. It keeps the telomeres from degrading which stops the natural clock for a normal cell’s death extends a cell’s life

Carcinogenesis

process by which normal cells are transformed into cancer cells-accumulation of mutation in a gradual, step like process

TGF-Beta

Transforming growth factor-growth factor protein that is produced in G1, aids in contact inhibition-signals cells to stay out of each other’s way

p53

Tumor suppressor gene that is present in G2-checks for mutations

Cell Cycle

series of events in which a cell grows, prepares for division, and divides to form two daughter cells

Cell Division

The process by which a cell divides into two new identical daughter ells with equal number of chromosomes 46 (how mny chromosomes are in the parent cell?)

Cancer

Any malignant growth or tumor caused by abnormal and uncontrolled cell division

Interphase

DNA is copied, check and prepped for Mitosis (synthesis phase)

Mitosis

cell division in which the nucleus divides into nuclei containing the same number of chromosomes, diploid (2n)

Cytokinesis

division of the cytoplasm of the newly formed conjoined daughter cells, occurs after mitosis, it cleaves/separates the cytoplasm conjoined daughter cells

G1

1st stage of Interphase: Cell growth- uses growth factors to make sure the cell is ‘not too big’ but ‘not too small’ stimulates cell division-growth factors, cell has enough nutrients and energy, cell is large and mature. What proteins that code/make for growth factors?

S phase

The 2nd stage of interphase: the synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated. Uses chromosomes form the nucleus- copies original DNA strand into a semiconservative DNA molecule, uses DNA polymerase for complementary pairing

G2

3rd stage of Interphase: Final preparation phase: The cell checks for DNA errors and begins to form centrosomes. (Prepares for Mitosis) G2 checkpoint makes tumor-suppressing proteins, checks and fixes DNA, too many errors- signals apoptosis

Sister Chromatids

Identical copies of a chromosome; full sets of these are created during the S subphase of interphase

Centromere

Region of a chromosome where the two sister chromatids attach