AP BIOLOGY UNIT 4 (copy)

* Make sure to know the mechanisms of the negative/positive feedbacks covered in class, * Know where the sister chromatids, centromere, and kinetochore would be on a chromosome, * Be able to identify/describe key events that take place in the cell cycle

Direct contact

Communication through cell junctions

Gap junctions

Between animal cells, used in direct contact

Plasmodesmata

Between plant cells, used in direct contact

Hormones

Used in long distance signaling

In direct contact communication, animal cells communicate through ______ junctions and plant cells communicate through _______.

gap, plasmodesmata

What do animals and plants use for long distance signaling? Differentiate between animals and plants when they use this to communicate.

Plants release hormones that travel through the vascular tissue and animals use endocrine signaling through the circular system

Differentiate between paracrine signaling and synaptic signaling.

Paracrine signaling uses secretory cells to release local regulators via exocytosis, synaptic signaling uses neurons to secrete neurotransmitters in animal nervous systems

True or false: insulin signaling is an example of local signaling.

False

Reception

The detection and receiving of a ligand by a receptor in the target cell

Transduction

The conversion of an extracellular signal to an intracellular signal that will bring about a cellular response

Receptor

A macromolecule that binds to a signal molecule

Ligand

A signal molecule

Second messengers

Small, non-protein molecules and ions help relay the message and amplify the response

GPCR

G protein coupled receptor- largest category of cell surface receptors important in animal sensory systems

Ligand-gated ion channel

Ion channel located in the plasma membrane important in the nervous systems, which acts like a "gate" for ions

Protein kinase

Signal transduction pathway enzyme that phosphorylates proteins

Protein phosphatase

Signal transduction pathway enzyme that dephosphorylates proteins

cAMP

Cyclic AMP, most common second messenger

Response

The final molecule in the signaling pathway that converts the signal to a response that will alter a cellular process

Summarize the three stages of cell signaling in one sentence each.

Reception: the ligand binds to the receptor. Transduction: the signal is converted. Response: The cell process is altered.

If you were given a problem on the AP exam that described a water-soluble (polar) receptor, where would it be located in the cell?

The cell membrane

Receptors bind to estrogen, a hormone would be found where in the cell?

Plasma membrane

What do second messengers do, and why is this role so important in some cells?

Second messengers amplify the signal in the signal transduction pathway

Second messengers amplify the signal in the signal transduction pathway

Protein kinase phosphorylates proteins and protein phosphatase dephosphorylates proteins

What does the term "signal" refer to in a signal transduction cascade?

The ligand/information attached to the molecule

Neurons can participate in both local and long distance signaling. How is this possible?

Neurotransmitters send long distance signals

How are signals passed from outside of the cell to inside of the cell?

Signal transduction pathway

Describe the "response" that a cell can have to a signal.

Genes shut on and off, alters membrane permeability, the enzyme will change the metabolic activity

How is it possible that a single signal molecule can elicit massive cellular responses?

The signal is amplified by second messengers.

What is transcription and translation (as it pertains to DNA)?

Transcription is when DNA is converted to RNA, and translation is when RNA produces proteins

True or false: the final molecule in a signal transduction pathway can act as a transcription factor, meaning that it can turn genes off or on.

True

What does it mean if a gene is turned off vs. on?

Stops and starts transcription for specific responses.

What would happen to the signal transduction pathway if protein phosphatase was mutated?

It would be unable to dephosphorylate receptors/relay proteins, which ultimately does not terminate the pathway

What would happen to the signal transduction pathway if protein kinase was mutated?

It would be unable to phosphorylate receptors/relay proteins, which will make the pathway unable to work

If a receptor protein is mutated, can it receive a ligand? Why or why not?

No, because receptor/ligand bonds are highly specific

How can chemicals activate or inhibit a pathway? (i.e. what does "activate" mean and what does "inhibit" mean in terms of a signaling cascade?)

Chemicals can induce/increase productivity in a pathway (activate), or shut/block them off completely (inhibit)

Set points

Values for various physiological conditions that the body tries to maintain

stimulus

A variable that will cause a response

receptor/sensor

Sensory organs that detect a stimulus. This information is sent to the control center

effector

Muscle or gland that will respond

homeostasis

The state of relatively stable internal conditions. Detect and respond to a stimulus, maintains through feedback loops (think: balance)

disease

When the body is unable to maintain homeostasis

Negative feedback

Feedback that reduces the effect of the stimulus

Positive feedback

Feedback that increases the effect of a stimulus

Why is homeostasis often referred to as balance?

Because homeostasis is the balancing of conditions

How is cancer an example of an inability to maintain homeostasis?

The body is unable to regulate cell growth

True or false: all cells in the body must have ways to maintain homeostasis

True

What is the main difference between negative and positive feedback?

The increasing/reducing effect of the stimulus

What happens if the body CANNOT regulate homeostasis

Diseases such as cancer and diabetes will happen, and the body will likely die.

Cell cycle

The life of a cell from its formation until it divides

DNA

Molecule inside cells containing genetic information, responsible for development ad function of an organism

chromatin

Material in chromosomes of organisms consisting of protein, RNA, and DNA

chromosome

Nucleic acids carrying genetic information (genes)

histones

A group of basic proteins found in chromatin

nucleosomes

Basic structure unit of DNA packaging in eukaryotes

centromere

The region on each sister chromatid where they are most closely attached

kinetochore

Proteins attached to the centromere that link each sister chromatid to the mitotic spindle

Sister chromatids

A duplicated copy of chromosomes (when DNA is replicated)

genome

All of a cell's genetic information (DNA)

Somatic cells

Body cells that divide by mitosis, diploid (2n)

Gametic cells

Reproductive cells (eggs/sperm) that divide by meiosis, haploid (n)

Fill in the blank: Strings of nucleosomes form ____

chromosomes

Why are chromosomes so densely packed?

To allow for easier division

Differentiate between somatic and gametic cells

Somatic cells are body cells that divide by mitosis, gametic cells are reproductive cells that divide by meiosis

How many chromosomes do humans have? How many of these are from mom and how many are from dad?

46, 23 from each

What are the five stages of mitosis? (PPMAT&C)

Prophase, prometaphase, metaphase, anaphase, telophase and cytokinesis

Does mitosis occur in somatic or gametic cells?

Somatic cells

How does cytokinesis differ in plants and animals?

In animals, a cleavage furrow appears due to a contractile ring of actin filaments. In plants, vesicles produced by the Golgi travel to the middle of the cell and form a cell plate

Think back to unit 2, what filaments are involved in cytokinesis?

Actin filaments

If an egg cell has 20 chromosomes, then how many chromosomes would the somatic cells have?

40

checkpoints

Control points that regulate the cell cycle through stop and go signals

Cyclins

Proteins that are synthesized and degraded at specific stages of the cell cycle

Cyclin dependent kinases (CDKs)

Concentrations that remain constant through each phase of the cell cycle

Growth factors

Hormones released by cells that stimulate cell growth

Contact (density) inhibition

Cell surface receptors that recognize contact with other cells

Anchorage dependence

Cells that rely on attachment to other cells or the extracellular matrix to divide

mutation

Irregular changes

tumor

A mass of tissue formed by abnormal cells

malignant

An abnormality that is harmful

benign

An abnormality that is not harmful

metastasis

When cells separate from a tumor and spread elsewhere in the body

apoptosis

Programmed cell death

Describe what would happen to a cell if it does not pass the G1 checkpoint

It would enter a nondividing state (G0 phase)

What is G0? What types of cells are in G0?

G0 is a major checkpoint in the cell cycle, muscle and nerve cells are in G0.

Describe what would happen to a cell if it does not pass the G2 checkpoint.

The cell will stop and attempt to repair damage, which will go under apoptosis if unable to be repaired

True or false: the concentration of cyclins remains constant throughout the cell cycle.

False

List three types of external cell regulators

Growth factors, contact inhibition, anchorage dependence

Describe at least two ways a cancer cell differs from a normal cell

Cancer cells do not follow checkpoints, evade apoptosis, and divide infinitely when in culture

Explain how sun damage can potentially lead to skin care

Sun is damaging to skin cells and can cause mutations to occur after exposure

How are cancer cells able to leave the original tumor site and metastasis?

By moving through walls of nearby lymph nodes or blood vessels