unit 4 cell communication and cell cyle Flashcards

1
Q

cell to cell communication is critical for

A

function and survival of cells

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2
Q

cells communicate through 3 ways

A

direct contact, local signaling, and long distance signaling

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3
Q

direct contact

A

communication through cell junctions
- signaling substances can pass freely between adjacent cells

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4
Q

in direct communication animal cells communicate through ____ and plants communicate through _____

A

animals: gap junctions
plants: plasmodesmata

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5
Q

what is an example of direct contact?

A

immune cells: antigen presenting cells communicate to T-cells through direct contact

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6
Q

local regulators

A

a secreting cell will release chemical messages (local regulators) that travel a short distance through the extracellular fluid

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7
Q

paracrine vs synaptic signaling

A

paracrine: secrete cells release local regulators via exocytosis to an adjacent cells
synaptic: animals nervous system
-nuerons secrete neurotransmitter
- diffused across synaptic cleft (space between the nerve cell and target cell)

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8
Q

long distance signaling

A

both animals and plants use hormones for long distance

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9
Q

plants vs animals long distance signaling

A

plants: release hormones that travel in the plant (xylem or phloem) to reach target issues
animals: use endocrine signaling
- cell releases hormones in the circulatory system where they reach target cells

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10
Q

insulin

A

released from the pancreas into the bloodstream and bind to target cells
- tells liver cells to take out excess sugar

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11
Q

what communication involves a cell secreting a substance to an adjacent cell

A

paracrine signaling

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12
Q

cell-to-cell stages

A

reception, transduction, response

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13
Q

describe reception, transduction, and response

A

reception: ligand binds to receptor
transduction: signal is converted
response: a cell process is altered

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14
Q

what is a receptor.

A

macromolecule that binds to a signal molecule (ligand)

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15
Q

any ligand can bind to any receptor T or F

A

false

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16
Q

when the ligand binds to receptor, the receptor…

A

activates (via a conformational change) which allows the receptors to interact with other cell molecules

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17
Q

plasma membrane receptors are identified as

A

polar, water- hydrophilic, large
ex: G protein coupled receptors
ligand-gated ion channels

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18
Q

intracellular receptors are identified as

A

in the cytoplasm, hydrophobic, steroid and thyroid hormone, gasses like nitric oxide

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19
Q

what is transduction and what does it require

A

the conversion of an extracellular signal into a intracellular signal that will bring about cellular response and requires changes in a series of molecules (signal transduction pathway)

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20
Q

transduction regulates protein activity though

A
  1. phosphorylation by the enzyme protein kinase (help relay signals inside the cells)
  2. dephosphorylation by the enzyme protein phosphatase (shuts down pathway)
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21
Q

during transduction the signal is _____

A

amplified

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22
Q

what are second messengers?

A

small, non-protein molecules help relay the message and amplify the signal
-cyclic AMP (gets signal stronger)

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23
Q

stage 3: response

A

converts signal to a response that will alter a cellular process
ex:
a. protein that can alter membrane permeability
b. enzyme that will change metabolic process
c. protein that will turn genes off and on

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24
Q

how is the signal passed from outside the cell to inside?

A

during transduction the signal is relayed by protein kinase and amplified by second messengers

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25
Q

signal transduction pathways can result in

A

gene expression, cell function, alter phenotypes or result in death

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25
Q

____ to receptors proteins will result in a ____ to the transduction of the signal

A

mutations, change

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26
Q

GPCR’s

A
  • binds to g protein that can bind to GTP
  • ligand binds to extracellular side, activating the G protein and GPCR (GDP–GTP). After g protein binds to enzyme which will amplify signals and lead to a cellular response
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27
Q

ion channels

A

nervous system , receptors act as a gate for ions.
- when a ligand binds to the receptor, the “gate” opens or closes allowing the diffusion of ions –> cellular response

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28
Q

set points

A

values for various physiological conditions that the body tries to maintain
ex; body temp

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29
Q

homeostasis

A

the state of relatively internal conditions
- organisms detect and respond to a stimulus

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30
Q

stimulus

A

a variable that will cause a response

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31
Q

receptor/sensor

A

sensory organs that detect a stimulus (sent to the brain)

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32
Q

effector

A

muscle or gland that will respond

33
Q

response

A

changes the effect of the stimulus

34
Q

negative feedback

A

reduces the effect of the stimulus
-sweat, blood sugar (insulin), breathing rate

35
Q

positive feedback

A

increases the effect of the stimulus
- child labor, blood clotting, fruit ripening

36
Q

why would do the body not regulate homeostasis?

A

genetic disorders, drug or alcohol, intolerable conditions (cold or heat)

37
Q

disease

A

when the body is unable to maintain homeostasis
- cancer: the body cannot regulate cell growth
- diabetes: the blood cannot regulate blood glucose levels

38
Q

during transduction the signal is _____

A

amplified

39
Q

in order to maintain homeostasis, cells must ____

A

communicate through signal transduction pathways

40
Q

describe the response that a cell can have to a signal

A

Once a receptor protein receives a signal, it undergoes a conformational change, which in turn launches a series of biochemical reactions within the cell.

41
Q

what does it mean when genes are turn off and on?

A

off: no longer able to provide directions for creating proteins
on: the gene is being transcribed into mRNA which then translates into a protein.

42
Q

what would happen to the signal transduction pathway of protein phosphatase was mutated

A

A malfunctioning protein phosphatase would not be able to dephosphorylate a particular receptor or relay protein. Would not be able to terminate

43
Q

what would happen to the signal transduction pathway of protein kinase was mutated

A

it will disrupt the entire signal pathway.

44
Q

cell cycle

A

the life of a cell from its formation until it divides

45
Q

DNA associates around _____ known as ______ to form ______

A

proteins, histones, nucleosomes

46
Q

strings of nucleosomes form ____

A

chromatin

47
Q

After DNA replication, ___ condenses to form a ____

A

chromatin, chromosomes

48
Q

centromere

A

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

49
Q

kinetochore

A

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

50
Q

genome

A

all of a cell’s genetic information (DNA)

51
Q

prokaryote vs eukaryote genome

A

prokaryotes: singular, circular DNA
eukaryote: one or more linear chromosomes
Humans: 46
Chimps:48
Elephants: 56

52
Q

homologous chromosomes

A

2 chromosomes that are the same length , have the same centromere position, and carry genes controlling the same characteristics

53
Q

somatic vs gamete cells

A

somatic: body cells, diploid (2n)- 2 sets. of chromosomes, one from each parent, divide by mitosis, 46 chromosomes
Gametes: reproduction cells (egg/sperm), haploid cells (n)- one set of chromosomes, divide by meiosis, n=23, only contain moms or dad genetic material

54
Q

G1 phase

A

the cells grows and carries out functions

55
Q

s phase

A

DNA replication and chromosome duplication occurs

56
Q

g2 phase

A

final growth and preparation for mitosis

57
Q

mitosis

A

nucleus divides

58
Q

cytokinesis

A

cytoplasm divides

59
Q

mitosis results in

A

2 identical diploid daughter cells

60
Q

Prophase

A
  • chromatin condenses
  • nucleoi disappear
  • duplicate chromosomes appear as sister chromatids
  • mitotic spindle will begin forming
  • centrosomes move away from each other
61
Q

prometaphase

A
  • nuclear envelope fragments
  • microtubules enter nuclear area and some attach to kinetochores
62
Q

metaphase

A

-centrosomes are at opposite poles
- chromosomes line up at the metaphase plate
- microtubules are attached to each kinetochore

63
Q

anaphase

A

-sister chromatids separate and move to opposite ends of the cell due to the microtubules shortening
- cell elongates

64
Q

telophase

A
  • two daughter nuclei form
    -nuclei reappear
  • chromosomes become less condensed
65
Q

cytokinesis

A

animal: cleavage furrow appears due to a contractile ring of actin filaments
plants: vesicles produced by the Golgi travel to the middle of the cell and form a cell plate

65
Q

G1 checkpoint

A
  • checks for cell size, DNA damage, and growth factors
  • Go- cell completes the whole cycle
    -Stop- cell enters a nondividing (quiescent) state known as G0
66
Q

G0

A

-some cells stay in G0 (muscle/nerve cells)
-some cells will go back into the cell cycle

67
Q

G2 checkpoint

A

checks for completion of DNA replication and DNA damage
- Go- cells proceeds to mitosis
- Stop- cell cycle stops and the cell will attempt to repair damage (if damage cannot be repaired the cell will undergo apoptosis)

68
Q

M (spindle) checkpoint

A
  • check for microtubule attachment to chromosomes at kinetochores at metaphase
  • go- cell proceeds to anaphase. and completes mitosis
  • stop- cell will pause mitosis to allow spindles to finish attaching to chromosomes
69
Q

cyclins as an internal cell cycle regulator

A
  • concentration of cyclins varies
    -cyclins are synthesized and degraded at specific stages of the cell cycle
70
Q

cyclin dependent kinases (CDK’s) -cycle regulator

A
  • concentration remains constant through each phase of the cell cycle
  • active only when a specific cyclin is present
71
Q

each cyclin-CDK complex has a _____ regulatory effect

A

specific
- active CDK complexes phosphorylate target proteins which help regulate key events in the cell cycle.

72
Q

growth factors

A

hormones released by cells that stimulate cell growth
- signal transduction pathway initiated
- CDK’s are activated leading to progression through the cell cycle

73
Q

contact (or density) inhibition

A

cell surface receptors recognize contact with other cells
- initiates the signal transduction pathway that stops the G1 phase in the cell cycle

74
Q

anchorage dependence

A

cells rely on attachment to other cells or extracellular matrix to divide

75
Q

normal cells become cancerous through ____

A

DNA mutations (changes in DNA)
- cancer cells on average have accumalated 60 or more mutations on genes that regulate cell growth

76
Q

normal. vs cancer cells

A

normal:
-follow checkpoint
- divide on average 20-50 times in culture (petri dish)
- go through apoptosis when there are significant errors
Cancer:
-doesn’t follow a checkpoint
- divide infinitely when in culture
- considered to be immortal
- evade apoptosis and continue dividing even with errors

77
Q

the uncontrollable growth of cancer cells can lead to ___

A

tumor (a mass of tissue formed by abnormal cells)

78
Q

benign tumor

A

cells are abnormal but not considered to be cancerous
- cells remained at only the tumor site and are unable to spread elsewhere in the body.

79
Q

malignant tumor

A

mass of cancerous cells that lose their anchorage dependency and can leave the tumor site