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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
Q

Each chromosome must be duplicated (replicated) before cell division

A

Duplicated chromosome = 2 sister chromatids attached by a centromere

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26
Q

Somatic Cells

A

Body cells
Diploid (2n): 2 of each type of
chromosome
Divide by mitosis
Humans: 2n = 46

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27
Q

Gametes

A

Sex cells (sperm/egg)
Haploid (n): 1 of each type of
chromosome
Divide by meiosis
Humans: n = 23

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28
Q

Phases of the Cell Cycle

A

The mitotic phase alternates with interphase: G1 → S → G2 → mitosis → cytokinesis

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29
Q

Interphase

A

(90%+ of cell cycle)

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30
Q

G1 Phase

A

cell grows and carries out normal functions

31
Q

S Phase

A

duplicates chromosomes (DNA replication)

32
Q

G2 Phase

A

prepares for cell division

33
Q

M Phase

A

(mitotic)

34
Q

Mitosis + PMAT

A

nucleus divides
prophase, metaphase, anaphase, telophase

35
Q

Cytokinesis

A

cytoplasm divides

36
Q

More on Mitosis

A

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
Q

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

A
38
Q

Cytokinesis

A

Cytoplasm of cell divided
Animal Cells: cleavage furrow
Plant Cells: cell plate forms

39
Q

During anaphase

A

Chromosomes walked to poles by motor proteins
Kinetochore microtubules shorten at ends as they depolymerize

40
Q

Bacterial cells divide by..

A

Binary Fission

41
Q

*** Checkpoint

A

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
Q

Major Checkpoints

A

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
Q

G2 checkpoint

A

Controlled by DNA replication completion, DNA mutations, cell size

44
Q

M-spindle (Metaphase) checkpoint

A

Check spindle fiber (microtubule) attachment to chromosomes at kinetochores (anchor sites)

45
Q

Internal Regulatory Molecules

A

Kinases, Cyclins, MPF

46
Q

Kinases

A

(cyclin-dependent kinase, Cdk): protein enzyme controls cell cycle; active when connected to cyclin

47
Q

Cyclins

A

proteins which attach to kinases to activate them; levels fluctuate in the cell cycle

48
Q

MPF

A

maturation-promoting factor
specific cyclin-Cdk complex which allows cells to pass G2 and go to M phase

49
Q

External Regulatory Factors

A

Growth Factor, Density-Dependent Inhibition, Anchorage Dependence,

50
Q

Growth Factor

A

proteins released by other cells
to stimulate cell division

51
Q

Density-Dependent Inhibition

A

crowded cells normally stop dividing; cell-surface protein binds to adjoining cell to inhibit growth

52
Q

Anchorage Dependence

A

cells must be attached to another cell or ECM (extracellular matrix) to divide

53
Q

Cancer

A

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
Q

Transformation

A

Process that converts a normal cell to a cancer cell

55
Q

Tumors

A

mass of abnormal cells

56
Q

Benign tumor

A

lump of cells remain at original site

57
Q

Malignant tumor

A

invasive - impairs functions of 1+ organs (called cancer)

58
Q

Metastasis

A

cells separate from tumor and travel to other parts of body

59
Q

Cancer Cells

A

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
Q

Treatment

A

Surgery, radiation, chemotherapy
Personalized Medicine:
Breast Cancer: 20-25% tumors show high HER2 receptors → use Herceptin to block HER2 protein

61
Q

Cancer Prevention

A

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
Q

WHAT IS HOMEOSTASIS?

A

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
Q

NEGATIVE FEEDBACK

A

Keeping the body in balance (homeostasis) to limit extreme conditions
Most body responses are controlled by negative feedback

64
Q

3 Components of Negative
Feedback

A

Sensor, control center, effector

65
Q

Sensor

A

Detects the change (body is
getting too warm)

66
Q

Control Center

A

Receives signal (usually the brain) from sensor and sends message to effector

67
Q

Effector

A

Reverses the initial change (skin
pores begin to perspire and blood vessels dilate)

68
Q

EXAMPLES of Negative Feedback

A

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
Q

Low body core temperature caused by cold temperature

A

our skin pores stop perspiring and
muscles contract (shiver) to generate heat

70
Q

High blood CO2 levels (carbon dioxide) caused by
intense exercise

A

our body increases respiration and
heart rate to remove excess CO2 and deliver more oxygen rich blood to our muscles.

71
Q

High blood glucose levels caused by eating a candy bar

A

our body releases insulin to remove the blood sugar into our cells

72
Q

POSITIVE FEEDBACK

A

Continual increasing of a response
until a final product is reached
This response occurs faster to
guarantee the product

73
Q

Example of Positive Feedback

A

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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