AP Bio Unit 6

What are the phases for mitosis?

Prophase, Metaphase, Anaphase, Telophase (PMAT)

What occurs during Prophase in mitosis?

Already duplicated DNA condenses into 2 sister chromatids, Centrosomes sprout mitotic spindles and move to opposite poles of the cell, nuclear envelope disintegrates

What occurs during Metaphase in mitosis?

Kinetochore protein forms at the centromere of chromosomes and mitotic spindles attach to the kinetochore, mitotic spindles align chromosomes in the middle of the cell

What occurs during Anaphase in mitosis?

Sister chromatids are pulled apart into opposite poles of the cell

What occurs during Telophase in mitosis?

Nuclear membrane forms around chromosome, which unwind into chromatin forms

What occurs during Cytokinesis in animal cells?

A ring of proteins "squeezes" cytoplasm, creates 2 cells

What occurs during Cytokinesis in plant cells?

Vesicles form together to make a cell plate, which becomes a cell membrane and cell wall

What are centrosomes/centrioles?

An organelle that houses the mitotic spindles

What are centromeres?

Center of chromosome structure where kinetochore attaches

What are kinetochores?

A protein that mitotic spindles attach to to pull chromatids apart

What is the metaphase plate?

The middle of the cell where chromosomes are lined up during metaphase

What is are sister chromatids?

Identical copies; “half of the X”

What is a chromosome?

Molecule that has all of the genetic material of an organism

What is a chromatin?

The less condensed and more extended form of genetic material (zooming in on chromosome)

What are homologous chromosomes?

2 different copies of a chromosome (one from each parent)

What is a haploid cell?

A cell that contains half the normal amount of chromosomes (1n); gametes (sperm/egg) are haploids

What are diploid cells?

A cell that contains two complete sets of chromosomes (2n), with each set from one of the parents

What are somatic cells?

Any cells in the body except for reproductive cells; contains full set of chromosomes (2n)

What are sex cells?

Gametes (sperm/egg) that contain half the normal amount of chromosomes (1n)

What are the 3 phases of interphase?

G1, S, G2

What happens during G1 phase?

Cell increases in size and prepares to replicate its DNA

What happens during S phase?

The cell duplicates DNA; the cell has 2 complete sets of chromosomes by the end of this phase

What happens during G2 phase?

The cell finishes growing and prepares for division; 2 centrosomes appear in the cytoplasm

What are the 3 major checkpoints?

G1, G2, M

Where is the G1 checkpoint, and what does it look for?

Occurs near the end of phase, looks to see if DNA is undamaged and there are enough resources for the cell to continue growing

Where is the G2 checkpoint, and what does it look for?

Occurs near the end of phase, looks to see if chromosomes are fully replicated and without damage

Where is the M checkpoint, and what does it look for?

Occurs during metaphase, looks to see if all sister chromatids are attached to mitotic spindles

What is differentiation?

The process in which cells with unspecified functions change to become specialized cells with specific functions

What is apostasies?

Cell suicide

What is G0?

Cells can exit G1 phase and enter G0, a nondividing state; neurons and muscle cells are fully differentiated cells that remain in G0

What causes cells to enter G0?

Cell was signaled to differentiate or resources are insufficient to grow and divide

What is the cell damage control system?

When cell division stops, the damage repair system is activated to repair whatever damage, the cell will self-destruct if the damage is too severe

What are internal controls in the cell cycle?

Internal factors that regulate the cell cycle; CDKs, checkpoint mechanisms, tumor suppressor genes, damage response

What are external controls in the cell cycle?

Signals and factors that originate outside the cell; Anchorage-dependent inhibition, density-dependent inhibition, growth factors

What are growth factors?

Proteins released by certain cells that stimulate other cells to divide

What is density-dependent inhibition?

Crowded cells stop dividing

What is Anchorage-dependent inhibition

Cells must be anchored to a substrate to divide

What is transformation?

The process in which a cell undergoes changes that lead to the development of cancerous cells

What is a benign tumor?

Abnormal cells stay at original site and will not grow or become dangerous (not cancerous)

What is a malignant tumor?

Has invaded surrounding tissues, has the potential to keep growing and spread (stage I-III)

What is a Metastasis?

Malignant cells have spread from the original site to other organs/parts of the body; secondary tumors present (stage IV)

How does radiation affect cancer?

Destroys cells in localized areas by damaging DNA and preventing replication

How does chemotherapy affect cancer?

Chemicals that inhibit DNA replication, cell division, cell growth

What is a downside to chemotherapy?

It affects all cells; can lead to hair loss

What are tumor suppressor genes (car brakes)?

Encodes proteins involved in suppressing cell division at checkpoints

What happens if a tumor suppressor gene is mutated?

When 6-9 genes are mutated, it loses function and cannot suppress cell division

What are oncogenes (car accelerator)?

Genes that have the potential to cause cancer when they are mutated or overexpressed

What happens when oncogenes are mutated?

It gains function or over expresses a certain gene

What are kinases?

Enzymes that add a phosphate to other proteins to activate or inhibit their function (phosphorylation)

What are CDKs?

A crucial regulator that is always present but only becomes active when bound to cyclin proteins; Cyclin concentration fluctuates throughout cell cycle

What is meiosis?

The production of gametes

What is mitosis?

Cell division

What happens during Meiosis 1?

Separates homologous pairs (2n —> 1n)

What happens during Meiosis 2?

Separates sister chromatids (just like mitosis)

Where does meiosis occur in animals?

Testes and Ovaries

What occurs in Prophase 1?

Homologous chromosomes come together (synapsis) forming a tetrad, and Crossing Over occurs

What is Crossing Over and why is it important?

Homologous pairs swap pieces of chromosomes; increasing genetic diversity and creates new trait combos

What occurs during Metaphase 1?

Mitotic spindles align tetrads along the middle of cell

What is independent assortment?

The “side” that each chromosome lines up on during metaphase 1 is random; increases genetic diversity

What occurs during Anaphase 1?

Homologous chromosomes are pulled apart, but sister chromatids remain attached together

What occurs during Telophase 1?

Cell splits into 2 (same as mitosis)

What is a karyotype?

Visual representation of the number, size, and shape of chromosomes in an individual's cells

How many chromosomes do humans have in total?

46 total chromosomes, 23 in gametes

What are regulator organisms?

Uses internal control mechanisms to stay stable in the face of external fluctuations

What are endotherms?

They have a high metabolic rate to maintain a high and stable internal temperature

What are conformer organisms?

They allow internal conditions to vary with external conditions

What are exotherms?

They have a low metabolic rate, and body temperature is determined by the environment

What is homeostasis?

Maintain an internal balance regardless of external conditions; body temp, pH, blood sugar

What are the mechanisms for homeostasis?

Fluctuations above or below a set point serve as a stimulus; these are detected by a sensor and trigger a response

What is negative feedback?

A corrective response to stimulus; homeostasis in animals relies largely on negative feedback

What is an example of negative feedback?

When blood sugar levels are too high, insulin is released which tells the liver and body cells to take in glucose and store it, reducing blood sugar levels

What is positive feedback?

Amplifies a stimulus and does not usually contribute to homeostasis in animals

What is an example of positive feedback?

When baby pushes against cervix, oxytocin is released, oxytocin causes uterus to contract and baby is pushed further toward cervix

What is acclimization?

Process of becoming accustomed to a new climate or to new conditions

What is an example of acclimization?

Fish are often acclimated to the water before they are released into a new fish tank

What is signal transduction pathway?

The process of causing cellular response after a signal molecules attaches to the receptor

What are local regulators?

Messenger molecules that can diffuse to the target cell which causes a response

What is paracrine signaling?

Communicate using secreted messenger molecules/local regulators; targets nearby cells

What is an example of paracrine signaling?

Growth factors stimulate nearby cells to grow and divide

What is synaptic signaling?

Neurotransmitters cross the small space between neurons or space between neuron and muscle cell

What is an example of synaptic signaling?

Touching hot stove and reflexively pulling away

What is endocrine signaling?

Hormones (proteins/lipids) are secreted in the bloodstream; targets cells far away

What is an example of endocrine signaling?

Adrenalin rush

What are the 3 stages for cell signaling?

Reception, Transduction, Response

What occurs during Reception for cell communication?

Signaling molecule (ligand) binds to receptor protein causing it change shape which initiates transduction

What occurs during Transduction for cell communication?

Chain reaction of molecular interactions relay signals from receptors to target molecules in the cell; can greatly amplify signals (telephone game)

What occurs during Response for cell communication?

Leads to regulation of transcription or cytoplasmic activity; often activates transcription factors which leads to protein synthesis

What is G-protein coupled reception?

Ligand attaches to G-protein receptors causing G-protein to get phosphorylated (GDP → GTP), activated G-protein moves over and activates enzymes which causes cellular response

What is Tyrosine Kinase reception?

2 ligands bind to each receptor tyrosine kinase which get energized and move together forming dimer, ATP “drops off phosphate” creating a fully phosphorylated dimer which trigger relay proteins and cause cellular response

What is Ligand Gated ion channel reception?

Ligand attaches to receptor causing it to open which allows ions to flow into cell and cause cellular response

What are the 3 types of receptors?

G-protein-coupled, Tyrosine kinase, Ligand-gated ion channel

What are transcription factors?

A protein that attaches to DNA and begins protein synthesis process

What is phosphorylation cascade?

A chain reaction of protein phosphorylation (inactive protein kinase gets activated which then goes and activates another inactive protein kinase)

What are second messengers?

Small, nonprotein, water soluble, molecules or ions that spread throughout the cell (middle man in communication)

What are examples of second messengers?

cAMP, Ca, IP3