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AP Biology > Unit 4: Cell Communication and the Cell Cycle #2 > Flashcards

Unit 4: Cell Communication and the Cell Cycle #2 Flashcards

1
Q

What is homeostasis?

A

The state of relatively stable internal conditions, like body temperature (97-99), and the body maintains homeostasis through feedback loops (organisms detect and respond to a stimulus)

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2
Q

What are the two types of feedback loops?

A

Negative and positive

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3
Q

What is a stimulus?

A

A variable that will cause a response

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4
Q

What is a receptor/sensor?

A

Sensory organ that detects a stimulus, this information is sent to the control center (brain)

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5
Q

What is an effector?

A

A muscle or gland or organ that responds to a stimulus

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6
Q

What are the responses to stimuli?

A

Changes that decrease or increase the effect of the stimuli

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7
Q

What is negative feedback?

A

Negative feedback is the most common mechanism and it reduces the effect of the stimulus.

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8
Q

What are some examples of negative feedback?

A

Sweat, blood sugar, breathing rate

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9
Q

How does the process of negative feedback happen?

A

First a stimulus is sensed by a receptor which sends the info to the brain, which sends a signal to the effector, which then creates a response that pushes the body back to homeostasis.

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10
Q

What is positive feedback?

A

Positive feedback increases the effect of a stimulus, and it is not as common.

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11
Q

What are examples of positive feedback?

A

Child labor, blood clotting, fruit ripening.

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12
Q

How does the process of positive feedback happen?

A

First the stimulus signals to the receptor to send the information to the brain, which tells the effector to create a response and this response amplifies the signal, creating a loop.

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13
Q

What could cause the body to not regulate homeostasis?

A

Genetic disorders (most common), drug or alcohol abuse, and intolerable conditions (ex. extreme cold)

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14
Q

What is the formal definition for disease?

A

When the body is unable to maintain homeostasis

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15
Q

What is the cell cycle?

A

The life of a cell from its formation until it divides (G1, S, G2, M)

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16
Q

How is a strand of DNA condensed to chromatin

A

DNA wraps around proteins known as histones (4 of them) to form nucleosomes, and strings of nucleosomes tightly wound form chromatin, which is DNA in its NON condensed form.

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17
Q

Why do chromatin condense to form chromosomes?

A

They condense and are densely packed to allow for easier division.

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18
Q

What are sister chromatids?

A

The two copies of each chromosome that join together to make an X shape.

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19
Q

What is the centromere?

A

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

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20
Q

What is the kinetochores?

A

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

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21
Q

What are cohesions?

A

Proteins that hold sister chromatids together (in between the kinetochores)

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22
Q

What is the genome?

A

All of a cell’s genetic information (DNA)

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23
Q

What type of DNA do prokaryotes have?

A

Singular, circular DNA

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24
Q

What type of DNA do Eukaryotes have?

A

One or more linear chromosomes, and each eukaryote has a specific number of chromosomes (humans 46)

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25
Q

What are somatic cells?

A

Body cells that are diploid, divide by mitosis, and have 46 chromosomes (23 from each parent)

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26
Q

What are gametes?

A

Reproductive cells (eggs/sperm) that are haploid, divide by meiosis, and have 23 chromosomes

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27
Q

What are diploid cells?

A

Cells that have two sets of chromosomes, one set from each parent

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28
Q

What are haploid cells?

A

Cells that have one set of chromosomes

29
Q

What stages are in interphase?

A

Gap 1 (G1), Synthesis of DNA (S), and Gap 2 (G2) (takes up 90% of the cell cycle)

30
Q

What is G1?

A

G1 is Gap 1 and it is where the cell grows and carries out normal function (most of the time the cell is in this phase)

31
Q

What is S?

A

S is the synthesis phase, where DNA replication and chromosome duplication occurs

32
Q

What is G2?

A

G2 is the second gap phase, which was the final growth and preparation stage for mitosis

33
Q

What happens in the M phase?

A

Mitosis happens, and the nucleus divides (also cytokinesis: where the cytoplasm divides), and the result is 2 identical diploid daughter cells

34
Q

What are the 5 stages of mitosis?

A

Prophase, (Prometaphase), Metaphase, Anaphase, Telophase (and cytokinesis)

35
Q

What happens in prophase?

A

The Chromatin condenses, nucleolus disappears, duplicated chromosomes appear as sister chromatids, mitotic spindle begins to form, centrosomes move away from each other

36
Q

What happens in prometaphase?

A

The nuclear envelope fragments, microtubules enter nuclear area and some attach to kinetochores

37
Q

What happens in metaphase?

A

Centrosomes are at opposite poles, chromosomes line up at the metaphase plate, microtubules are attached to each kinetochore

38
Q

What happens in anaphase?

A

Sister chromatids separate and move to opposite ends of the cell due to the microtubules shortening, and the cell elongates

39
Q

What happens in telophase?

A

Two daughter nuclei form, nucleoli reappear, chromosomes become less condensed, and cytokinesis occurs

40
Q

What happens in cytokinesis in animals?

A

In animals, a cleavage furrow appears due to a contractile ring of actin filaments (microfilaments)

41
Q

What happens in cytokinesis in plants?

A

Vesicles produced by the Golgi travel to the middle of the cell and form a cell plate for the cell wall

42
Q

What is the G1 checkpoint?

A

The most important checkpoint that checks for cell size, growth factors, and DNA damage

43
Q

What are the outcomes for the G1 checkpoint?

A

The cell either passes, and completes the cell cycle, or the cell stop sand enters a nondividing state known as G0

44
Q

How long do cells stay in G0

A

Muscle and nerve cells stay in G0 forever, but some cells can be balled back into the cell cycle

45
Q

What does the G2 checkpoint do?

A

It checks for the completion of DNA replication and DNA damage

46
Q

What are the outcomes of G2 checkpoint?

A

If it passes, the cell proceeds to mitosis, if it stops, the cell cycle stops so the cell can repay damage, and if it is not repaired the cell with undergo apoptosis

47
Q

What is the M (Spindle) Checkpoint?

A

It checks for microtuble attachment to chromosomes at the kinetochores at metaphase

48
Q

What are the outcomes of the M (spindle) checkpoint?

A

If it passes, the cell proceeds to Anaphase and completes mitosis, if it doesn’t the cell with pause mitosis to allow for spindles to finish attaching to chromosomes.

49
Q

What are the two types of cell cycle regulators?

A

Internal regulators and external regulators

50
Q

What are the two things that are used in internal cell cycle regulation?

A

Cyclins and CDKs (cyclin-dependent kinases)

51
Q

What macromolecule is a cyclin and what macromolecule is a CDK?

A

They are both proteins and CDKs are enzymes

52
Q

What is the concentration of cyclins like?

A

The concentration varies, with cyclins being synthesized and degraded at specific stages of the cell cycle, in order to push forward the cell cycle and be like a “clock” to decide whether the cell with undergo mitosis or not. Keeps the pace.

53
Q

What is the concentration of CDKs like?

A

Concentration of CDKs are constant through each phase of the cell cycle, because they are only active when its specific cyclin it is binding to is present

54
Q

How does the CDK-cyclin complex work?

A

The Cyclin binds to the CDK to form this complex, the CAK gives it a phosphate, and then the complex binds to a target protein and phosphorylates that (and that protein with advance the cell cycle) Each cyclin-CDK complex has a specific regulatory effect

55
Q

How are CAKs used?

A

For full activation, many CDKs also require phosphorylation by a Cyclin Activating Kinase (CAK) to ensure that the CDK-cyclin complex is fully active and can effectively phosphorylate its substrates to drive the cell cycle forward

56
Q

What are the three types of external cell cycle regulators?

A

Growth factors, Contact (or density) Inhibition, and anchorage dependence

57
Q

What are growth factors?

A

Hormones that are released by cells that stimulate cell growth through signal transduction pathways that activate CDKs (think cell signaling)

58
Q

What is contact/density inhibition?

A

When cell surface receptors recognize contact with other cells, they initiate a signal transduction pathway that stops the cell cycle in the G1 phase

59
Q

What is anchorage dependence?

A

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

60
Q

How do normal cells usually become cancerous?

A

Through DNA mutations, cancer cells on average have accumulated 60 or more mutations on genes that regulate cell growth

61
Q

Compare and contrast cancer cells and normal cells.

A

Normal cells follow checkpoints, cancer cells do not, normal cells divide 20-50 times in culture, cancer cells divide indefinitely, normal cells go through apoptosis when necessary, cancer cells evade it

62
Q

What is a tumor?

A

It results from the uncontrollable growth of cancer cells and it is a mass of tissue formed by them

63
Q

What are the two types of tumors?

A

Benign and malignant

64
Q

What is a benign tumor?

A

It is when the cells are abnormal but not cancerous yet, and are unable to spread elsewhere in the body

65
Q

What are malignant tumors?

A

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

66
Q

What is metastasis?

A

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

67
Q

How is blood glucose levels a negative feedback?

A

When there is too little sugar in your bloodstream (for cellular respiration), the pancreas detects it and releases glucagon to increase it by breaking down glycogen into glucose, and when there is too much, the pancreas detects it and releases insulin to lower it by building glycogen from glucose.

68
Q

Are you ready for the test?

A

1-5

AP Biology (8 decks)

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