Random Kid Thing for BIo

Cell Division

The reproduction of cells

Cell Cycle

The process by which the cell grows, prepares for division, and divides into two daughter cells.

Why do cells divide?

Cell differentiation in multicellular organisms (growth)

Cell reproduction (asexual or sexual)

Repair

Why is cell growth limited? (explanation)

Bigger cells have a more difficult time maintaining cell function

Volume increases faster than surface area

Why is cell growth limited? (exact points)

DNA overload

Problems moving nutrients and wastes

Surface area (cell membrane) to volume (cytoplasm and organelles) becomes too large

How are some of the cells in our body so large?

They have very odd shapes that give them a lot of surface area

What are the two main stages of the cell cycle?

Mitotic phase (M) & Interphase

What phase does the cell cycle mostly consist of?

Interphase

What are the subphases of interphase?

Gap 1 (G1), Synthesis (S), and Gap 2 (G2)

What must happen before mitosis can occur?

The cell must get to a specific size and the DNA must be undamaged

Describe Gap 1

The cell grows while maintaining regular function

Describe the synthesis phase

DNA is replicated and checked for error/damage

Describe Gap 2

Additional growth and checking DNA

What is Gap 0 (G0)?

When the cell stops the cell cycle and does not divide

How is the rate of cell division determined?

The need for those types of cells

Why is cell cycle regulation necessary? (key concept)

Cell cycle regulation is necessary for healthy growth.

What is the cell cycle control system?

The system used to ensure that everything that needs to happen in the cell cycle does happen by using checkpoints (functions like a clock)

How is the cell cycle control system regulated?

The cell cycle control system is regulated by both internal and external controls

How does the cell cycle control system regulate the cell cycle

specific checkpoints where the cell cycle stops until a go-ahead signal is received

Which is the most important checkpoint?

The G1 checkpoint

What happens if a cell passes the G1 checkpoint?

The cell will usually complete the cell cycle

What happens if a cell does not pass the G1 checkpoint?

It enters G0 (enters apoptosis if it fails certain other checkpoints)

What are the regulatory proteins involved in internal cell cycle regulation?

cyclins and cyclin-dependent kinases (Cdks), their activity fluctuates during the cell cycle

What is MPF?

MPF (maturation-promoting factor) is a cyclin-Cdk complex that triggers a cell's passage past the G2 checkpoint into the M phase

Name an example of when an internal regulation would occur

An example of an internal signal is that kinetochores not attached to spindle microtubules send a molecular signal that delays anaphase.

What do external factors do?

They trigger internal factors

What is a type of external signal the cell may recieve?

Growth factors are proteins released by certain cells that stimulate other cells to divide

What are some examples of growth factor?

platelet-derived growth factor (PDGF) stimulates the division of human fibroblast cells in culture

Most mammal cells form a single layer in a culture dish and stop dividing once they touch other cells.

What is apoptosis?

Apoptosis is programmed cell death.

a normal feature of healthy organisms

caused by a cell's production of self-destructive enzymes

occurs indevelopmentof infants

What is special about cancer cells?

Cancer cells do not respond normally to the body's control mechanisms

Cancer cells may not need growth factors to grow and divide

What do cancerous cells do regarding cell cycle control systems and growth factor?

They may make their own growth factor

They may convey a growth factor signal without the presence of the growth factor

They may have an abnormal cell cycle control system

What is it called when a healthy cell becomes cancerous?

Transformation

What is a tumor?

A mass of abnormal cells

What is a benign tumor?

A tumor that stays clustered and can be removed relatively easily

What is a malignant tumor?

A tumor that grows more aggressively and has a high chance of spreading

Define metastasize

When a malignant tumor breaks off to form more tumors

Do cancer cells carry out regular function?

No

How do cancer cells happen?

Cancer cells come from normal cells with damage to genes involved in cell-cycle regulation.

What are carcinogens?

Carcinogens are substances known to promote cancer.

What is a negative side of recieving cancer treatment?

Standard cancer treatments typically kill both cancerous and healthy cells.

When do cells divide? (key concept)

Mitosis & cytokinesis

What is the genome?

All the DNA in a cell constitutes the cell's genome

What does the genome consist of?

A genome can consist of a single DNA molecule (common in prokaryotic cells) or a number of DNA molecules (common in eukaryotic cells)

What is a chromosome?

Really really condensed DNA

How does the DNA prepare for cell division?

The DNA is replicated and condensed into chromosomes

What are histones?

Proteins that DNA wraps around. Histones assist in condensing the DNA

What is a sister chromatid?

When you divide the DNA along the vertical half, there are 2 sister chromatids on each side

What happens to the sister chromatids in cell division?

One is taken to one daughter cell and the other goes to the other daughter cell.

What is the centromere?

The "waist" (middle bit) where the sister chromatids are attached to eachother

What is a telomere?

The telomere is the bit at the end of the chromatid that is only there to protect the DNA

What is produced through cellular division?

Two genetically identical daughter cells

What happens during prophase?

Chromosomes condense, the nuclear envelope breaks down, and centrioles (centrosomes) move to opposite poles to do spindle formation. An aster extends from each centrosome to anchor the centriole to the cell membrane (the centrosome also replicates in prophase)

What is the centrosome?

microtubule organizing center

What is the mitotic spindle?

The mitotic spindle is an apparatus of microtubules that controls chromosome movement during mitosis

What is an aster?

a radial array of short microtubules

What is the spindle made of?

The spindle includes the centrosomes (pairs of centrioles), the

spindle microtubules, and the asters

What happens during prometaphase?

Some of the spindle microtubules attatch to the kinetochores of the chromosomes and start moving them

What happens during metaphase?

spindle fibers attach to each chromosome. They align the chromosomes along the cell's equator, called the metaphase plate. (basically finishing prometaphase)

What happens during anaphase?

The sister chromatids spearate and move to the different sides of the dividing cell

How do the microtubules shorten?

The microtubules shorten by depolymerizing at their kinetochore ends

What happens during telophase?

During telophase, the nuclear envelope starts to reform and chromosomes begin to uncoil. The spindle fibers also start to fall apart.

What is cytokinesis? What forms in plant and animal cells during cytokinesis?

Cytokinesis is the division of the cytoplasm. In animal cells, a clevage furrow forms and in plant cells, a cell plate forms.

What is binary fission?

The process by which a prokaryote reproduces

What happens in binary fission?

the chromosome replicates (beginning at the origin of replication), and the two daughter chromosomes actively move apart. The cell then divides into two daughter cells

What is the purpose of cell division in single celled organisms?

Reproduction

What is asexual reproduction?

The production of genetically identical offspring from a single parent

What is the purpose of cell division in multicellular organisms?

Multicellular organisms depend on cell division for:

Development from a fertilized cell

Growth

Repair

When would asexual reproduction be advantageous?

Asexual reproduction is an advantage in consistently favorable conditions because the offspring are genetically identical.

When would sexual reproduction be advantageous?

Sexual reproduction is an advantage in changing conditions because offspring are genetically different from the parents.

What do specialised cells do?

Specialized cells perform specific functions.

What is cell differentiation?

The process by which cells reach their mature form in multicellular organisms. They can differentiate into different types of cells

Why are cells with the same DNA different?

different combinations of genes are expressed.

What determines how a cell will differentiate?

A cell's location in an embryo

What are tissues?

Tissues are groups of cells that perform a similar function.

What are organs?

Organs are groups of tissues that perform a specific or related function

What are organ systems?

Organ systems are groups of organs that carry out similar functions.

What are the five levels of cellular organisation?

Cell > tissue > organ > organ system > organism

What is special about stem cells?

Stem cells have the ability to:

divide and renew themselves

remain undifferentiated in form

develop into a variety of specialized cell types

What are the three types of stem cells?

totipotent, pluripotent, multipotent

What is a totipotent stem cell?

a cell that can differentiate into any cell type

What is a pluripotent stem cell?

cells that have the capacity to develop into many different types of cells