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AP Bio > Unit 4 : Cell Communication & Cell Cycle > Flashcards

Unit 4 : Cell Communication & Cell Cycle Flashcards

1
Q

Animal Cells communicate by:

A

Direct contact (gap junctions)
Secreting local regulators (growth
factors, neurotransmitters)
Long distance (hormones)

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2
Q

3 types of cell signaling

A

Reception
Transduction
Response

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3
Q

Reception

A

Detection of a signal molecule (ligand) coming from outside the cell

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4
Q

Transduction

A

Convert signal to a form that can bring about a cellular response

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5
Q

Response

A

Specific cellular response to the signal molecule

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6
Q

Reception (Full concept)

A

Binding between signal molecule (ligand) + receptor is highly
specific.
Types of Receptors: Plasma membrane receptor & Intracellular receptors
Ligand binds to receptor protein→protein changes SHAPE →initiates transduction signal

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7
Q

Plasma Membrane Receptor

A

water-soluble ligands

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8
Q

Intracellular receptors

A

(cytoplasm, nucleus)
small or hydrophobic ligand molecules
Eg. testosterone or nitric oxide (NO)

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9
Q

Transduction (full concept)

A

Cascades, Protein kinase, Phosphorylation cascade

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10
Q

Cascades…

A

of molecular interactions relay signals from receptors → target molecules

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11
Q

Protein kinase

A

enzyme that phosphorylates and
activates proteins at next level

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12
Q

Phosphorylation cascade

A

enhance and amplify
signal

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13
Q

Second Messengers

A

small, nonprotein molecules/ions that can relay signal inside cell
Ex: cyclic AMP (cAMP), calcium
ions (Ca2+), inositol triphosphate
(IP3)

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14
Q

cAMP

A

cAMP = cyclic adenosine monophosphate
GPCR → adenylyl cyclase (convert ATP → cAMP) → activate protein kinase A

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15
Q

Response (full concept)

A

Regulate protein synthesis by turning on/off genes in nucleus (gene expression)
Regulate activity of proteins in cytoplasm

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16
Q

Signal Transduction Pathway
Problems/Defects

A

Diabetes
Cholera
Autoimmune disease
Cancer
Neurotoxins, poisons, pesticides
Drugs (anesthetics, antihistamines, blood pressure meds)

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17
Q

Cholera

A

Disease acquired by drinking contaminated water (w/human feces)
Bacteria (Vibrio cholerae) colonizes lining of small intestine and **produces toxin which modifies G-protein involved in regulating salt & water secretion
G protein stuck in active form → intestinal cells secrete salts, water
Infected person develops
profuse diarrhea and could die
from loss of water and salts

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18
Q

Viagra

A

Used as treatment for erectile dysfunction
Inhibits hydrolysis of cGMP → GMP
Prolongs signal to relax smooth muscle in artery walls; increase blood flow to penis

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19
Q

Apoptosis

A

CELL SUICIDE
Cell is dismantled and digested
Triggered by signals that activate cascade of “suicide” proteins (caspase)
WHY? Protect neighboring cells from damage
Animal development & maintenance
May be involved in some diseases (Parkinson’s, Alzheimer’s)

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20
Q

Cell Cycle

A

life of a cell from its formation until it
divides into 2 cells

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21
Q

Functions of Cell Division

A

Reproduction, Growth &
Tissue Repair

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22
Q

Genome

A

all of a cell’s genetic info (DNA)

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23
Q

Prokaryote

A

single, circular chromosome

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24
Q

Eukaryote

A

More than one linear chromosomes
Eg. Human:46 chromosomes, mouse: 40, fruit fly: 8

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25
Each chromosome must be duplicated (replicated) before cell division
Duplicated chromosome = 2 sister chromatids attached by a centromere
26
Somatic Cells
Body cells Diploid (2n): 2 of each type of chromosome Divide by mitosis Humans: 2n = 46
27
Gametes
Sex cells (sperm/egg) Haploid (n): 1 of each type of chromosome Divide by meiosis Humans: n = 23
28
Phases of the Cell Cycle
The mitotic phase alternates with interphase: G1 → S → G2 → mitosis → cytokinesis
29
Interphase
(90%+ of cell cycle)
30
G1 Phase
cell grows and carries out normal functions
31
S Phase
duplicates chromosomes (DNA replication)
32
G2 Phase
prepares for cell division
33
M Phase
(mitotic)
34
Mitosis + PMAT
nucleus divides prophase, metaphase, anaphase, telophase
35
Cytokinesis
cytoplasm divides
36
More on Mitosis
Continuous process with observable structural features: Chromosomes become visible (prophase) Alignment at the equator (metaphase) Separation of sister chromatids (anaphase) Form two daughter cells (telophase & cytokinesis)
37
IMPORTANT *** Checkpoint if theres a mutation it'll cause cancer ESPECIALLY IN G2 bc its last one in interphase before mitosis so NO CHANGING DNA before that
38
Cytokinesis
Cytoplasm of cell divided Animal Cells: cleavage furrow Plant Cells: cell plate forms
39
During anaphase
Chromosomes walked to poles by motor proteins Kinetochore microtubules shorten at ends as they depolymerize
40
Bacterial cells divide by..
Binary Fission
41
*** Checkpoint
Control point where stop/go signals regulate the cell cycle If theres a mutation it'll cause cancer ESPECIALLY IN G2 bc its last one in interphase before mitosis so NO CHANGING DNA before that
42
Major Checkpoints
G1 checkpoint (Most important!) Controlled by cell size, growth factors, environment “Go” → completes whole cell cycle “Stop” → cell enters nondividing state (G0 Phase) Nerve, muscle cells stay at G0; liver cells called back from G0
43
G2 checkpoint
Controlled by DNA replication completion, DNA mutations, cell size
44
M-spindle (Metaphase) checkpoint
Check spindle fiber (microtubule) attachment to chromosomes at kinetochores (anchor sites)
45
Internal Regulatory Molecules
Kinases, Cyclins, MPF
46
Kinases
(cyclin-dependent kinase, Cdk): protein enzyme controls cell cycle; active when connected to cyclin
47
Cyclins
proteins which attach to kinases to activate them; levels fluctuate in the cell cycle
48
MPF
maturation-promoting factor specific cyclin-Cdk complex which allows cells to pass G2 and go to M phase
49
External Regulatory Factors
Growth Factor, Density-Dependent Inhibition, Anchorage Dependence,
50
Growth Factor
proteins released by other cells to stimulate cell division
51
Density-Dependent Inhibition
crowded cells normally stop dividing; cell-surface protein binds to adjoining cell to inhibit growth
52
Anchorage Dependence
cells must be attached to another cell or ECM (extracellular matrix) to divide
53
Cancer
Disorder in which cells lose the ability to control growth by not responding to regulation. Multistep process of about 5-7 genetic changes (for a human) for a cell to transform Loses anchorage dependency & density-dependency regulation
54
Transformation
Process that converts a normal cell to a cancer cell
55
Tumors
mass of abnormal cells
56
Benign tumor
lump of cells remain at original site
57
Malignant tumor
invasive - impairs functions of 1+ organs (called cancer)
58
Metastasis
cells separate from tumor and travel to other parts of body
59
Cancer Cells
Some have abnormal #’s of chromosomes Metabolism disabled Lose attachment to ECM → spread to other tissues Signaling molecules cause blood vessels to grow toward tumor
60
Treatment
Surgery, radiation, chemotherapy Personalized Medicine: Breast Cancer: 20-25% tumors show high HER2 receptors → use Herceptin to block HER2 protein
61
Cancer Prevention
Anyone can get cancer but there are ways to minimize risk: Don’t smoke, legal or illegal (includes hookahs, chew, 2nd-hand smoke) Use sun protection Exercise and keep weight at ideal level Eat 5-7 servings of fruit and veggies a day Use screening/preventative measures-breast/testicle/mole checks Practice abstinence or use condoms Vaccines (eg. HPV)
62
WHAT IS HOMEOSTASIS?
Organisms stay alive by maintaining a stable internal environment. Depends on the interactions of body systems to maintain balance. Homeostasis is in jeopardy when internal and external conditions becomes too extreme
63
NEGATIVE FEEDBACK
Keeping the body in balance (homeostasis) to limit extreme conditions Most body responses are controlled by negative feedback
64
3 Components of Negative Feedback
Sensor, control center, effector
65
Sensor
Detects the change (body is getting too warm)
66
Control Center
Receives signal (usually the brain) from sensor and sends message to effector
67
Effector
Reverses the initial change (skin pores begin to perspire and blood vessels dilate)
68
EXAMPLES of Negative Feedback
Low body core temperature caused by cold temperature, High blood CO2 levels (carbon dioxide) caused by intense exercise, High blood glucose levels caused by eating a candy bar
69
Low body core temperature caused by cold temperature
our skin pores stop perspiring and muscles contract (shiver) to generate heat
70
High blood CO2 levels (carbon dioxide) caused by intense exercise
our body increases respiration and heart rate to remove excess CO2 and deliver more oxygen rich blood to our muscles.
71
High blood glucose levels caused by eating a candy bar
our body releases insulin to remove the blood sugar into our cells
72
POSITIVE FEEDBACK
Continual increasing of a response until a final product is reached This response occurs faster to guarantee the product
73
Example of Positive Feedback
During pregnancy, the uterus contracts as soon as labor begins, which pushes the baby’s head against the cervix. This causes the body to release oxytocin, a hormone, to increase the contractions until baby is born.

AP Bio (8 decks)

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