ap bio unit 4 cell communication and cell cycle test review

ligand

a chemical messenger that binds to a receptor, resulting in a transduction pathway that often ends with a transcription of a specific gene sequence

local regulators

short distance chemical signals used for autocrine or paracrine signaling

transcription factor

proteins that regulate the reading of genes to produce mRNA that will then go on to produce a protein; these proteins help RNA polymerase bind to DNA

gene

a chunk/segment of a DNA strand, ranging from a couple hundred nucleotides to a couple million nucleotide that code for specific proteins

protein kinase

an enzyme that will activate other proteins by phosphorylating them (facilitate transfer of a phosphate onto them)

g-protein coupled receptor

diverse group of membrane bound receptors that undergo conformational change to initiate a transduction pathway i

ion channel linked receptor

a ligand binds to this integral membrane protein, opening a channel to allow secondary messengers to pass through; sometimes they’re voltage gated proteins

negative feedback mechanisms

maintain homeostasis by regulating physiological processes; return system back to target set point

positive feedback mechanisms

amplify responses and processes in biological organisms; variable initiating response is moved farther away from the initial set point

amplification

(feedback loops) stimulus is further activated, initiating an additional response that produces change in the system

mitosis

type of asexual reproduction of cells in a multicellular organism that produces genetically identical daughter cells from the parental cells; distributing replicated chromosomes to daughter nuclei to initiate the formation of 2 new identical cells

• how all other cells are created (except sex cells)

• creates at an exponential rate

true

t/f: interphase is generally the same in mitosis and meiosis

prophase

• Nuclear membrane breaks down

• Chromatin condenses and chromosomes become visible 

• Centromeres and kinetochore proteins

• Centrioles and spindle fiber microtubules appear

chromosomes— 46

chromatids— 92

how many chromosomes does the cell have during prophase? chromatids?

prophase

metaphase

metaphase

• Chromosomes line up @ equatorial line of the cell

• Spindle fiber microtubules attached to centromere kinetochores of the chromosome

• Helps prevent nondisjunction

anaphase

• Spindle fibers are attached to the centromeres of each chromosome

• Sister chromatids are pulled apart to opposite sides of the cell

  • Chromosomes are pulled apart

anaphase

telophase

• Chromosomes @ opposite sides of cells

• Nuclear membrane reforming

• Chromosomes untangling

• Nucleolos returning

• Centrioles and spindles are going away

• Nucleus returning to normal

telophase

cytokinesis

• Separation of cells

• Cells move apart and officially form 2 daughter cells

• Animal cells - a cleavage furrow forms where the cytoplasm will be pinched off

• Plant cells - cell plate forms where the 2 membranes meet and the cell wall will form

cytokinesis

interphase

G0- checkpoint, opportunity for apoptosis, lag point

G1- major growth phase, creates organelles for cell function

S- DNA duplication

G2- cell creates organelles and molecules for division

the time between cell divisions when a cell is carrying out normal functions and/or preparing for mitotic division; where most of a cell’s life is spent, longest phase

**not part of mitosis

G0

checkpoint, opportunity for apoptosis, lag point; where cells wait for the right time to grow/divide, sometimes entered when something went wrong during cell division

G1

major growth phase, creates organelles for cell function

S

DNA duplication; puts cells on the trajectory to divide

G2

cell creates organelles and molecules for division

kinase

enzyme that catalyzes the transfer of a phosphate group from ATP to a specific molecule (phosphorylation)

cyclin-dependent kinases (CDKs)

regulate transcription, mRNA processing, and differentiation of nerve cells; moves cell through G1, S, G2, and M phases

• 2 identical diploid daughter nuclei 

• Nuclei are part of somatic cells

• Separation of nucleus, not the cell

• Cytokinesis separates cell

what are the results of cell division and mitosis?

which proteins are in the cell

what does specialization/differentiation depend on?

differentiation

process by which during development newly formed cells become more specialized and distinct from one another as they mature

false

t/f: genomes may be different in different cells of an organism

activation of genes within a cell causes it to signal for differentiation

what causes cells to differentiate?

breaks down messengers and/or stimulatory proteins by breaking ester bonds

-esterase

PLC (phospholipase)

typically stimulated by g-proteins or tyrosine kinases, these hydrolyze lipid-based compounds to form the secondary messengers IP3 and DAG

conformational change

a change in the shape of a macromolecule, typically proteins, as induced by another molecule or environmental factors

G protein

a family of proteins tat act as molecular switches inside cells, transmitting signals from a variety of stimuli following their release from a transmembrane receptor

cAMP, IP3, Ca²+ (also DAG and NO)

secondary messengers examples

secondary messengers

stimulate proteins, leading to a response in a transduction pathway

tyrosine kinase

family of enzymes in the cell membrane that mediate multiple responses following dimerization to imitate transduction pathways pertaining to proliferation, metabolism, and apoptosis

phosphorylation cascade

a sequence of signaling pathway events where one enzyme phosphorylates others, causing a chain reaction that amplifies a signal/response

adenylyl cyclase

an enzyme that synthesizes cAMP to amplify a transduction pathway

phosphorylation

when a phosphate is couple with a larger molecule, activating or inhibiting that molecule

ubiquitin

regulatory protein that tags proteins, directing their movement to a proteasome where they will be degraded/destroyed

1. to heal wounds or breaks

2. to stay small for better transport and efficiency

3. nucleus makes proteins at a limited rate

why do cells reproduce?

cell proliferation

the process of cells rapidly growing and dividing

growth factors

cells release proteins/hormones that bind to a cell to stimulate cell proliferation

• Regulate only a small portion of the cell cycle

• Cells deprived of growth factors enter G0, when growth factors are added they will return to division

cyclins

proteins that are made internally and destroyed rapidly; stimulate certain stages of the cell cycle 

kinase

enzyme that transfers a phosphate group from ATP to another molecule (typically a protein), causing it to change shape and become energized

proto-oncogens

overactive form of proteins that are associated with cancer

• Cancer cells don’t respond to signals that regulate growth and reproduction of cells; thus divide uncontrollably, absorb excessive nutrients, block nerve connections, prevent invaded organs from functioning normally 

• Growth causes change in shape (and thus function)

oncogene

a cell causing cancer; mutated

contact inhibition

when cells come into contact with other cells, they’re programmed to stop dividing and form tight gap junctions & desmosomes

receptor tyrosine kinase (RTKs)

membrane receptors that transfer phosphate groups from ATP to another protein 

• Can trigger multiple signal transduction pathways at once

• Abnormal functioning is associated w/ cancers; mutated form can’t attach to DNA to signal a stop for cell division 

1. Receptor mutation activates cell division pathway in the absence of an appropriate ligand 

1. Mutation results in loss of ability to produce a tumor suppressor protein

2. @ anaphase checkpoint, chromatids are separated w/o all centromeres being attached to kinetochore microtubules from both poles

what can cancer be caused by?

1. Apoptosis

2. Long cell cycles

3. Cell arrest until DNA is repaired

4. Failing to proceed to different stages

5. Functioning tumor suppressor or proto-oncogenes 

these 5 things are NOT cancer

apoptosis

cell is systemically dismantled and digested, triggered by signals that activate a cascade of suicide proteins

direct

gap junctions are what kind of contact between cells?

growth factors, neurotransmitters

ex of local regulators

hormones

ex of long distance singalong molecule

plasmodesmata

for cell-cell contact, plants use…

gap junctions

for cell-cell contact, animals use…

gap junctions and plasmodesmata

connect cytoplasm of 2 adjoined cells and pass on chemical signals quickly (including hydrophilic ones)

major histocompatibility complex

group of genes that code for proteins on the cell surface that help the immune system recognize foreign substances

paracrine signaling

form of local signaling, cells secrete short lived chemical signals to local cells to elicit a joined response

endocrine

form of distance signaling, production of hormones by glands that travel through the circulatory system to cells

reception

detection of signal molecule (ligand) from outside cell

transduction

convert signal to form that can cause cellular response

response

specific cellular response to ligand occurs in the nucleus or cytoplasm

plasma membrane receptor

water soluble, hydrophilic ligands involved in reception

intracellular receptors

inside the cytoplasm/nucleus, small or hydrophobic ligand molecules involved in reception

protein changes shape

ligand binds to receptor → _________ → initiates transduction signal

transduction

cascades of molecular interactions relay signals from receptors that move to target molecules

phosphorylation cascade

enhance and amplify signal by taking a phosphate from an ATP molecule and attaching it to an amino acid

secondary messengers

small, non protein molecules/ions that relay signals inside cells

cAMP

activities protein kinase A

ligand gated ion channel

acts as a gate when receptor changes shape, allows specific ions through

gene expression

what mainly happens during a response?

GLUT4

acts as a channel to let glucose in the cell

cells can grow more rapidly

why is asexual reproduction beneficial?

growth factors

proteins and hormones are examples of..

46

how many chromosomes are in a cell?

46

how many strands of DNA are in a cell?

prophase, metaphase, anaphase, telophase

what is the order of the phases of mitosis?

92

in anaphase and telophase, there are ___ chromosomes

endocrine

the thyroid and epinephrine are examples of what type of signaling?

synaptic signaling

uses a neuron to send a signal over a small gap to bind

kinetochore

protein that links chromatids to spindle fibers

quorum sensing

bacteria can sense the presence of other bacteria nearby using chemical signals

checkpoint

point in the cell cycle that stops to regulate the cell cycle and make sure it’s good to proceed

neurotransmitters

local regulators ex

negative

body temperature regulation is an example of what type of feedback response?

positive

birth and lactation are examples of what type of feedback loop?

protects neighboring cells from damage, used for animal development and maintenance  

what is apoptosis used for?

direct

the major histocompatibility complex uses which type of signaling?

phosphorylation, secondary messengers

transduction can occur by _______ or _______

amplify

transduction can cause the signal to do what?

insulin

used when there’s high blood sugar

glucagon

used when there’s low blood sugar