Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology 121 > Sheet 8--Test 3 > Flashcards

Sheet 8--Test 3 Flashcards

1
Q

What is the cell cycle?

A

Eukaryotes–> interphase (not dividing) and cell division

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what are the two main problems cells need to solve in order to divide, and which is more important?

A

Make sure there is two times as much cytoplasm and organelles
—more imporant= daughter cells get correct copy of genome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

how do prokaryotic cells divide?

A

Binary fission–asexual

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

how do prokaryotes know when they have finished replicating their genomes?

A

2 replication complexes meet on opposite sides of origin of replication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

where do bacteria add new cell wall and plasma membrane as they grow

A

between mesosomes (mesomes attach chromosomes to cell membrane)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How do prokaryotes ensure that each cell gets a copy of the genome after cell division?

A

..

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

how do eukaryotic cells divide?

A

Mitosis: division of genomes
–genome–> DNA of an organism
why Mitosis? growth, repair, replace

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

why is cell division more complicated in eukaryotic than in prokaryotic cells?

A

Genome is larger–> organelles must be replaced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

why is there so much protein associated with DNA in eukaryotes?

A

Organizes and compresses DNA

–spool (histone) of thread (DNA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is chromatin? and what is the differnce between heterochromatin and euchromatin?

A

State of chromosome when they are thin and spread out in nucleus during interphase
–chromatin is a mixture of protein, DNA and some RNA

Heterochromatin– highly condensed chromatin
Euchromatin– less condensed chromatin, can access genes–this is only condensed in mitosis to help move it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are histones?

A
  • -Proteins around which DNA wraps
    • +charge, DNA has - charge–> neutalized overall charge
  • -compress and organize DNA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are Nucleosomes, what is the function?

A
  • -Fundamental packaging unit of DNA
  • -each has 2 of H2A, H2B, H3, H4
  • -compress DNA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How can our cells compress 2 meters of DNA into a nucleus less that 10 nanometers in diameter?

A

DNA–> Nucleosome –> solenoids –> extended section chromosome –> condensed loop –> metaphase chromosome

Nucleosome–every 200nucleotides, DNA is coiled around 8 histone proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the 5 levels of compression

A

1) nucleosome
2) solenoid
3) extended section chromosome
4) condensed loop

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what are chromosomes?

A

structure in which genetic material is stored and transmitted to next generation
–DNA + Histones = Chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are chromatid?

A

identical copy of same DNA molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are homologous chromosomes?

A

similar copies of same DNA moleucle–get one from mom and one from dad
–have same length, position of centromere, same genes but the genes have different traits

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what are sister chromatids, and how do they differ from homologous chromosomes?

A

sister chromatids are identical copies of the same DNA molecule

homologous chromosomes are similar copies of the same DNA molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is a centromere?

A

site where sister chromatids are attached

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is a kinetochore?

A

protein attached to centromere to which microtubules attach

–spindle fiber = microtubule = protein fiber

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is a karotype and why is it useful?

A

array of individuals chromosomes

  • -can be used to detect genetic defects
  • – Aneuplody- differen # of chromosomes and cancer
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is ploidy?

A

number of homologous chromosomes
2m–diploid– 2 copies of each chromosome
–somatic cells, which are all cells except for gametes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what are the two stages and five divisions of the eukaryotic cell?

A

1) Interphase– G1, S (replicateDNA), and G2

2) Cell division– Mitosis and cytokinesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what are the three division of interphase and what happens during each?

A 
Interphase (longest phase)
G1
----Primary growth phase
---- phase
----Follows cytokinesis
----Make more of cell
----Determine if condition favor cell division
S 
----DNA synthesis
G2
----Quality control
----No DNA damage? Conditions ok to divide
----Chromosomes begin to condense
----Cells start building mitotic apparatus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What are the 4 phases of mitosis? and what happens?

A

..

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How are the chromosomes aligned on the metaphase plate?

A

microtubules pull chromosomes back and forth between asters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what holds the sister chromatids together during metaphase?

A

centromeres

28
Q

how are the chromosomes separated during anaphase?

A

microtubules shorten and pull sister chromatids apart

29
Q

what is the difference between mitosis and cytokinesis?

A

mitoisis is the division of nuclues and the distribution of chromosomes

cytokinesis is the division of the cytoplasm

30
Q

how do we know they are seperate proceses?

A

can poison one without affecting the other

31
Q

How do animals perform cytokinesis and how do plants perform cytokinesis?

A

..

32
Q

What are the main differences between cell division in plants and animals?

A

..

33
Q

Why dont plants need asters?

A

because they have cell walls that are regid

34
Q

How do eukaryotes regulate cell divsion?

A

– cell progresses through a series of checkpoints called G1, G2 and metaphase

35
Q

What checkpoint is most important and why is it the most important?

A
  • -G1 is most important
  • -asses if conditions are right because you dont want to copy DNA until ready.
  • -S phase follows G1–> S is the synthesis of DNA so it makes sense that G1 chekcs the DNA
36
Q

What is MPF and what does it do?

A

Mitosis promoting factor

  • -chemical that promotes mitosis–> it causes prophase (1st stage of mitosis)
  • -Need to make MPF in stage before prophase, which is G2.

Has 2 subunits:

1) catalytic subunit CDK
2) Regulatory unit is cuclin

37
Q

What are cyclins and what do

A
  • -regulate cell cycle
  • –determine what CDKs (enzyme) will act in and how active it will be
  • –different cyclins are made at different times, have to be attached to CDK for CDK to work
38
Q

How does SPF sense if a cell is ready to enter S. and how does it then initiate the transition to S?

A

Synthesis promoting factor–made during G1

  • -activated by a variety of sensors- Food?, DNA? cell large enough?
  • -if good, SPF turns on genes responsible for proteins that do DNA syntheis
  • -3 hour lag then DNA is synthesized
  • -SPF and MPF have same CDK, different Cyclin
39
Q

How does MPF sense if the cell is ready to divide and how does it initiate the transition to M?

A

MPF is activated by sensors for growth factors and amount of food–it is INHIBITED by DNA damage

  • -the transition to mitosis involves the phosphorlyations of proteins, especially nuclear lamins, which cause the nuclear membrane to break down
    • condenses chromosomes
  • -assemble mitotic appartus
40
Q

How is the metaphase checkpoint regulated?

A

Check:

    • are all chromosomes on metaphase plate?
  • -does each kinetochore have spindle fiber?

**this is checked by pulling chromosomes back and forth

41
Q

What is APC and what does it do?

A
  • -anaphase promoting complex
  • APC is inactive until all kinetochores are bound to microtubules
  • -triggers anaphase–sister chromatids separate as microtubules shorten
42
Q

Why must MPF be destruyed for cells to exit mitosis?

A

MPF keeps cells in mitosis

–when prophase is done, MPF must leave or it will stay in that stage

43
Q

How do multicellular organisms regulate cell division?

A
  • rely on the presence of growth factor at cell surface receptor
  • -sets off phosphorylation cascade that activates SPF. results is passing start
44
Q

Why do you get cancer when proto-oncogenes go wild?

A
  • -proto oncogenes are genes that normally activate cell division
    • if they become oncogenes, they no longer control cell division and cancer occurs
45
Q

Why do you get cancers when tumor surporessors go bad?

A

tumor supressors normally inhiit cell division

ex. Rb

46
Q

What is P53 and what does it do?

A

P53 senses DNA damage; halts cell until DNA is fixed active during G2

  • -70% of cancers have defective p53
    • DNA is replicated in S, G2, occurs after S so it is checking DNA that was replicated correctly
47
Q

What is Rb and what does it do?

A
  • -retinoblastoma protein–tumor supressor gene
  • -master break of cell cycle
  • -dephosphorylsted in G1
  • -releases then whem kinased by SPF
  • –SPF kinasaes Rb–> releases proteins needed for S
  • defective Rb allows these proteins to act too soon
  • *40% of cancers have defective Rb
48
Q

How do you recognize a plant cells in cytokinesis?

A

2 nuclei at opposite ends of cells

–formation of cell plate

49
Q

which phase of the cell cycle lasted longest in onion root tips?

A

interphase

50
Q

how can muscles get larger in adult humans?

A

increase size by increaseing the size fo cells, not by increasing cell number
–muscle cells do not do mitosis

51
Q

When does APC become inactive?

A

when all kinetochore are bound to microtubules

52
Q

what trigger anaphase?

A

APC

53
Q

when is MPF made? and does it trigger

A

G2 and it trigger mitosis

54
Q

what are the 2 subunits of MPF?

A

CDK and cyclin

55
Q

what is checked during metaphase?

A

1) all chromosomes are on metaphase plate

2) each kinetochore has spindle fibers connected

56
Q

how is chromosomes checked during metaphase?

A

by pushing and pulling chromosomes

57
Q

what is known as the master break of the cell cycle?

A

RB

58
Q

when is RB dephosphorylated?

A

G1

59
Q

what kinases Rb and what occurs when it is?

A

SPF kinases and it releases proteins needed to start S

60
Q

Bacterial cells divide as the?*

A

plasma membrane pinches inward constricting the cell

61
Q

What is ploidy?*

A

The number of copies of each homologous chromosome in a cell

62
Q

Which of the following is essentially the reverse of prophase?*

A

telophase

63
Q

The array of microtubules that appears in cell division and eventually moves the chromatids apart is the?*

A

spindle

64
Q

How do eukaryotic cells ensure that each daughter cell gets one copy of each homologous chromosome at cell division?*

A

they ensure that each chromosome has a microtubule from one pole attached to one kinetochore and a microtubule fro the other pole attached to the other before dividing.

65
Q

the proteins that control passage through the checkpoings for cell cycle control are ?*

A

cyclins and cyclin-dependent kinases

66
Q

what is checked at the G1 checkpoint?*

A

whether the cell should divide

67
Q

Why do you get cancers when proto oncogenes become hyperactive?

A

they promote cell division and thus over ride the ordinary control over cell division

Biology 121 (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions