Biology Final

The cell cycle

The regular pattern of growth, DNA, duplication, and cell division that occurs in eukaryotic cells.

What are the two main parts of the cell cycle?

Interphase and Mitosis (M Phase)

What stages make up interphase?

G1, Synthesis, G2

How long does the cell cycle take?

24 hours

What part of the cell cycle do cells spend most of their time in?

Interphase

What do cells carry out in interphase?

Cells carry out their normal functions, undergo critical growth, and prepare for cell division.

What happens to the cells during interphase?

During interphase, the cell increases in size. The DNA of the chromosome is replicated, and the centrosome is duplicated.

What happens during G1?

During G1, cells increase in size, and organelles increase in number. The cell must pass a critical checkpoint before it can proceed to the synthesis stage.

What do most animal cells need in order to function properly?

Most animal cells need enough nutrition, adequate size, and relatively undamaged DNA to divide successfully. They also need specific signals from other cells, telling them whether more cell division is needed.

Gap 1 (G1)

The 1st stage of interphase (11 Hours).

Where does G1 checkpoint occur?

It occurs before moving to Synthesis.

Synthesis

The 2nd stage of interphase (8 Hours).

What does Synthesis mean?

It means the combining of parts to make a whole.

What happens during the "S" stage?

During the "S" stage, the cell makes a copy of its nuclear DNA. By the end of the S stage, the cell nucleus contains two complete sets of DNA.

Where is DNA located in eukaryotes?

In eukaryotes, DNA is located in the nucleus.

Gap 2 (G2)

The 3rd stage of interphase (4 Hours).

What happens during G2?

During G2, cells continue to carry out their normal functions and additional growth occurs.

What does the G1 checkpoint check for?

G1 Checkpoint checks for cell size, nutrients, growth factors, and DNA damage.

What does the G2 Checkpoint check for?

The G2 Checkpoint checks for DNA damage and DNA duplication.

Mitosis

The division of the cell nucleus and its contents.

What happens during mitosis?

During mitosis, the nuclear membrane dissolves, the duplicated DNA condenses around proteins and separates, and two new nuclei form.

What are the two parts of the M phase?

Mitosis and Cytokinesis (1 Hour)

Cytokinesis

The process that divides the cell cytoplasm.

Where does the M Checkpoint occur?

It occurs near the end of the metaphase stage of mitosis.

What is the result of M phase?

2 daughter cells that are genetically identical to the original cell.

What happens to the cell in the G0 stage?

In G0, a cell is not actively preparing to divide, it is just doing its job.

G0 Stage

A permanent state for some, while others may restart division if they get the right signals.

What are some examples of G0?

Mature neutrons and white blood cells divide when needed.

What does the rate of cell division depend on?

The rate at which your cells divide depends on your body's need for those.

What organs' cells divide only occasionally, in response to injury or cell death?

Lungs, kidneys, and liver

Who has a faster rate of cell division than adults?

Embryos and children

What is the lifespan of a skin cell?

2 weeks

What is the lifespan of a red blood cell?

4 months

What is the lifespan of a liver cell?

300-500 days

What is the lifespan of the intestinal lining?

4-5 days

What is the lifespan of the intestinal tissues?

16 years

Why would babies and children have a faster rate of cell division than adults?

Babies and children grow more than adults.

Would a prokaryote cell divide faster or slower than an eukaryote?

A prokaryotic cell would divide slower than an eukaryotic because it does not have a nucleus.

How many chromosomes does the body have?

46 chromosomes

How many pairs of chromosomes does the body have?

23 pairs

Chromosome

One long continuous thread of DNA that consists of numerous genes along with regulatory information.

How much feet worth of DNA does a cell contain?

It contains about 6 ft-10 ft worth of DNA.

What is the 23rd chromosome pair called?

sex chromosomes (XX, XY)

DNA

A double-stranded molecule made of four subunits called nucleotides.

What proteins does DNA wrap around to help it fit inside the nucleus?

Histones

What is needed for DNA to be ready to divide?

Tight condensing

What happens if the DNA is divided when loose?

If the DNA is divided when loose, it would tangle up, causing potential errors in DNA.

What does each continuous double stranded DNA molecule make?

One chromosome

What does DNA wrapping around histones form?

Chromatin

Supercoiled DNA

The chromatin coils more and more tightly around organizing proteins.

When does chromatin condense?

It condenses before mitosis.

Chromatid

One half of the duplicated chromosome

Sister chromatid

The duplicated chromosome

What is the difference between a chromatin and a chromatid?

A chromatin is the material that makes up a chromosome, while a chromatid is one half of a replicated chromosome.

Where are the sister chromatids held together?

They are held together at a region of condensed chromosome that looks pinched (centromere).

Telomere

At the end of chromosomes are regions of non-coding DNA.

What is the purpose of telomeres?

Their purpose is to prevent the loss of genes and to keep the ends of chromosomes from attaching to each other.

Somatic cells

Cells that make up body parts and organs. It does not include sex cells which are sperm and egg cells.

What does mitosis occur in?

It occurs in somatic cells and all eukaryotic cells.

What is the purpose of mitosis?

The purpose is to replace old worn out cells and repair damaged tissue. It is also important for growth and development.

What are the phases of mitosis?

Prophase, Metaphase, Anaphase, Telophase (PMAT)

Is cytokinesis part of mitosis?

No, cytokinesis is not officially part of mitosis but it still needs to occur.

What takes place in Interphase?

Cell copies its DNA in preparation for division, DNA is loose, organelles have duplicated, and the cell is also large enough to divide.

Prophase

Chromatin begins to condense into tightly coiled chromosomes and they become visible. The nuclear envelope begins to break down, the nucleolus disappears. Centrosomes and centrioles begin to move to the opposite poles of the cell and spindle fibers begin to grow from the centrioles.

Metaphase

At this step, the centrosomes are already at the poles of the cell. The spindle fibers attach to the kinetochore. The chromosomes begin to align at the middle of the cell.

Kinetochore

A protein that is on the centromere of the chromosome.

Anaphase

During this stage, proteins that hold the sister chromatids together, break down causing them to separate. Spindle fibers shorten pulling the sister chromatids away from each other and towards opposite poles of the cell.

Telophase

In a telophase, a complete set of chromosomes arrive at the opposite poles and begin to uncoil. The nuclear envelope begins to form around the chromosomes. The spindle fibers break down.

True or False: Cytokinesis in animals and plants is different.

True

Cytokinesis in Animals

Membrane forms a furrow or trench (cleavage furrow) that is pulled inward like a drawstring.

Cytokinesis in Plants

Cells cannot pinch inward because of the cell wall, so they form a cell plate, which is made by the Golgi body.

What factors does the cell cycle have for all eukaryotic cells?

The cell cycle for all eukaryotic cells have internal and external factors then regulate it.

External factors

Outside the cell; messages from other cells.

Internal factors

Come from molecules within the cell's cytoplasm.

What do these factors together do for the body's cell division?

Together these factors help regulate the body's cell division.

What factors help regulate the cell cycle?

Factors that help regulate the cell cycle may be physical and/or chemical.

What is an example of a physical factor?

Cell to cell contact

What causes the cells to stop dividing?

Once the cells start to touch each other, they stop dividing.

What do many cells release and what does it cause them to do?

Many cells release chemical signals that tell other cells to grow.

What is an example of a chemical factor?

Growth factors

What do growth factors bind to?

They bind to specific receptors that turn on certain genes to trigger cell growth.

Gigantism

A condition caused by an overproduction of growth hormones, resulting in excessive bone growth.

Dwarfism

A condition caused by a lack of growth hormone.

What are the most common internal factors?

CDKs and Cyclins

What does CDK stand for?

Cyclin-Dependent Protein Kinase

Cyclin-CDK complex

Formed and then acts as a signal for the next cell cycle phase.

Apoptosis

programmed cell death

When apoptosis occur?

It occurs when internal and external factors turn on genes that tell the cell to produce self-destruct enzymes.

What is apoptosis needed for?

Apoptosis is needed to keep balance when new cells are formed.

How long does apoptosis occur in?

Occurs in about 2-3 hours

What effect does apoptosis have on human embryos?

Human embryos have webbed digits early in their development. The cells undergo apoptosis during late stages of development. As a result, the baby is born with unwebbed fingers and toes.

Syndactyly

A term used to describe webbed or conjoined digits (fingers or toes).

Cancer

An uncontrollable cell division disease.

What happens when regulations of the cell cycle breakdown?

When regulations of the cell cycle breakdown, cancer arises.

What happens when cells begin to divide uncontrollably?

When cells begin to divide uncontrollably, they created tumors.

Tumors

A mass of disorganized cell clumps.

What are the 2 types of tumors?

Benign and Malignant

Malignant

Unregulated, irreversible, has the ability to invade and metastasize, poorly differentiated, fast speed of growth, recurrence after removal, and often causes death

Benign

Unregulated, irreversible, does not have the ability to invade and metastasize, well differentiated, slow speed of growth, no recurrence after removal, and rarely causes death

Why are tumors harmful?

They don't perform their normal jobs. The body has large clumps of cells that require food and lots of blood but contribute nothing to the body.