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Bio 1/2 > "Unit 1" (4a, 4b, 7b) > Flashcards

"Unit 1" (4a, 4b, 7b) Flashcards

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Biology 101 flashcards
1
Q

Prokaryotes

A
  • Lack a nucleus
  • Single celled organism (unicellular)
  • bacterial cells
  • Have a single chromosome (a piece of circular, double-stranded DNA located in an area of the cell called the nucleoid)
    Reproduce by binary fission
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2
Q

how do prokaryotes reproduce

A

Reproduce via binary fission

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3
Q

whys cell division important

A

replication important process for organisms to undergo in order to survive

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4
Q

purpose of cell division

A

growth and development, maintenance and repair and reproduction.

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5
Q

what type of reproduction is Binary fission

A

Type of asexual reproduction

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6
Q

what reproduces via binary fission

A

Prokaryotes (e.g.bacteria) reproduce rapidly via binary fission (results in two genetically identical copies of a cell)

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7
Q

whats DESC stand for

A
  • DNA replication
  • Elongation
  • Septum formation
  • Cell division
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8
Q

how quick can cell division be in bacteria

A

can be completed can be completed in 20 minutes in some

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9
Q

binary fission step 1

A

The circular chromosome is uncoiled and the DNA is replicated. Plasmids also replicate.

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10
Q

Plasmid

A

small circular loop of DNA that is separate from a chromosome (typically found in bacteria)

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11
Q

binary fission step 2

A

the cell elongates (lengths) as it prepares to separate into two new cells and the duplicated circular chromosomes migrate to opposite ends.

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12
Q

binary fission step 3

A

cell undergoes cytokinesis; process of separating into two new cells
- by pinching inwards and creating a septum. Because plasmids replicate independently of the circular chromosome, these will not always be evenly distributed between the two new cells.

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13
Q

binary fission step 4

A

new cell wall and membrane are formed down the centre of the cell

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14
Q

binary fission step 5

A

then 2 genetically identical cells are formed

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15
Q

Exponential growth

A
  • Cells replicate exponentially (after each round of division the number of cells doubles)
  • Binary fission in bacteria rapidly multiplies a single bacterium into millions in a short time
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16
Q

Eukaryotes

A
  • non-bacterial cells
  • Contain a nucleus and membrane-bound organelle
  • Nucleus houses the cell’s DNA and directs the synthesis of proteins and ribosomes
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17
Q

how do eukaryotes replicate

A

Replication of cells occurs through cell cycle (mitosis)
(Skin cells - constantly regenerating them)

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18
Q

results of eukaryotic cell cycle

A
  • production of 2 new cells, each identical to the parent cell that gave rise to them
    (For a typical human, 24 hours are required to complete one cell cycle)
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19
Q

3 umbrella stages of the eukaryotic cell cycle

A

Interphase, mitosis, cytokinesis

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20
Q

Interphase

A

cell growth and duplication of chromosomes

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21
Q

Mitosis

A

separation of sister chromatids and the formation of 2 new nuclei

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22
Q

Cytokinesis

A

division of the cytoplasm and formation of two daughter cells

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23
Q

how do you know when the eukaryotic cell cycle of dividing is complete

A

its final/complete when you have the formation of the 2 daughter cells

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24
Q

cytoplasm

A

the jelly liquid that fills the inside of a cell

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25
Q

Sub stages in growth and division of the eukaryotic cell cycle and how long each stage goes for

A
  • G1 stage: 11 hours
  • S stage: 8 hours
  • G2 stage: 4 hours
  • M stage (Mitosis): 1 hour
  • Cytokinesis
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26
Q

Interphase

A
  • period of DNA replication
  • First and longest stage of cell cycle
  • cell synthesises the necessary DNA, proteins and organelles required for growth and replication
  • Nuclear DNA exists as chromatin threads rather than chromosomes
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27
Q

substages that are apart of interphase

A
  • Gap 1 (G1) phase
  • Synthesis (S) phase
  • Gap 2 (G2) phase
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28
Q

Gap 1 (G1) phase

A
  • first growth stage
  • cell prepares to copy its DNA
    (Protein and organelle synthesis for cell replication and growth)
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29
Q

in G1 phase how does cell prepares to copy its DNA and grows

A
  • Increasing the volume of its cytosol
  • Synthesising proteins required for DNA replication
  • Replicating its organelles
30
Q

what happens at the end of the G1 phase

A
  • cell either proceeds to S phase
  • or exits the cell cycle and enters G0 phase
31
Q

Gap 0 (G0) phase

A
  • Cells that are not required to replicate rest in the G0 phase
  • Cells in G0 are either quiescent or terminally differentiated
    (most cells don’t undergo GO phase)
32
Q

Quiescent

A
  • cells are dormant and have the ability to re-enter cell cycle.
    (eg: liver cells - can regenerate, even if a portion has been surgically removed or damaged)
33
Q

Terminally differentiated

A
  • cells are fully specialised and no longer replicate (remain in G0 indefinitely).
    (eg:) nerve cells - if damaged, cannot repair themselves or be replaced.
34
Q

Synthesis (S) phase

A
  • Cell replicates its DNA, turning one chromosome into 2 genetically identical sister chromatids
  • At end of S stage, the parent cell contains 2 identical copies of its original DNA
    (Chromosome replication)
35
Q

Gap 2 (G2) phase

A
  • Final stage of interphase
  • cell continues to grow and prepare itself for mitosis (Similar to G1 phase)
  • Cell continues increasing the volume of the cytosol.
  • Cell synthesises proteins in preparation for mitosis
    (continued cell growth)
36
Q

cytosol

A

one of the liquids found inside cells

37
Q

What is difference between cytoplasm and cytosol?

A
  • Cytoplasm is the substance between a cell’s membrane (its outside layer) and its nucleus (its core)
  • Cytosol is the fluid part of cytoplasm
38
Q

Mitosis (M phase)

A
  • Important part of cell cycle
  • involves organizing and separating replicated chromosomes into two new nuclei.
39
Q

mitosises 4 sub stages

A
  • Prophase
  • Metaphase
  • Anaphase
  • Telophase
40
Q

Chromosome condensation

A

shortening and thickening of chromosomes, as DNA is tightly coiled around histone proteins.

41
Q

Centrioles

A

cylindrical structures composed of protein which form the spindle fibres during mitosis

42
Q

Spindle fibres

A

structures which aid in the movement of chromosomes to either pole of the cell during mitosis and meiosis.

43
Q

Equator

A

centre line between opposite ends of the cell that the chromosomes line up on during metaphase

44
Q

Cleavage furrow

A

an indentation of the plasma membrane during cytokinesis.

45
Q

Cell plate

A

component involved in the formation of a cell wall

46
Q

Prophase process (mitosis)

A
  • first stage
  • DNA coils tightly and chromosomes condense becoming visible as distinct chromosomes (double-stranded structures)
  • Nuclear membrane breaks down and nucleolus disappears
  • Centrioles go to opposite ends (or poles) of the cell
  • Spindle fibres begin to form
47
Q

Metaphase process (mitosis)

A
  • second stage
  • spindle fibres fully form
  • spindle fibres attach to the centromere of each chromosome and guide the chromosomes towards the equator (middle) of cell (where they line up)
48
Q

Anaphase process (mitosis)

A
  • third stage
  • Spindle fibres contract (shorten), splitting the centromere of each chromosome
  • Sister chromatids are then pulled by the spindle fibres to opposite poles of the cell
49
Q

Telophase process (mitosis)

A
  • last stage
  • Separation of chromosomes is completed
  • Chromosomes densely pack together at either end of the cell
  • New nuclear membranes form around each separate group of chromosomes (producing two genetically identical nuclei)
  • Spindle fibres disintegrate and chromosomes gradually decondense (no longer visible as distinct chromosomes)
50
Q

Cytokinesis

A
  • Occurs after mitosis
  • the cytoplasm divides
  • the organelles evenly distribute themselves before separating into two genetically identical daughter cells
51
Q

where are the cell cycle checkpoints

A

3 check points; G1 checkpoint (before GO), G2 checkpoint, metaphase checkpoint

52
Q

why’s it necessary for the cell cycles to have check point

A

cell inspects itself for errors before proceeding to the next stage

53
Q

if any errors are detected, the cell….

A

can pause for repairs

54
Q

If the damage is irreparable, then the cell…

A

undergoes programmed cell death

55
Q

G1 Checkpoint checks and if it checks off what has to be done then what happens

A
  • If cell has grown to the correct size
  • If cell has synthesised enough protein for DNA replication
  • If original DNA has been damaged during mitosis and cell growth
  • If theres enough nutrients and oxygen

If a cell passes this checkpoint, it can advance to the S stage of cell cycle (if it does it will go into GO Phases)

56
Q

G2 Checkpoint checks and if it checks off what has to be done then what happens

A
  • DNA replicated properly in the S phase and theres no damage
  • cell has enough resources for mitosis

If a cell passes this checkpoint, it can advance to the mitosis stage of cell cycle.

57
Q

Metaphase (M) Checkpoint checks and if it checks off what has to be done then what happens

A
  • formation of the spindle fibres
  • spindle fibres are attached to the chromosomes correctly

If the chromosomes are lined up in the correct location, the cell proceeds to anaphase.

58
Q

Zygote

A

diploid cell formed by the combination of two haploid gamete cells

59
Q

Germline cell

A

cells that are involved in the generation of gametes in eukaryotes (dividing cell)

60
Q

Gonads

A

organs that produce gametes from germline cells

61
Q

Crossing over

A
  • exchange of genetic material between non-sister chromatids during prophase I
  • resulting in new combinations of alleles in daughter cells.
62
Q

Chiasma

A

point/location of overlap between two non-sister chromatids

63
Q

Independent assortment

A

random orientation of homologous chromosomes along the metaphase plate during metaphase I

64
Q

What is meiosis

A
  • specialised form of cell division that occurs in sexually reproducing organisms and is used to produce the gametes necessary for sexual reproduction.
65
Q

what are gametes in humans

A
  • sperm and egg (also known as ova) cells
  • contain only one copy of each chromosome (n) and will fuse together during fertilisation to create two copies of each chromosome (2n) inside a developing zygote.
66
Q

what’s meiosis involve

A
  • Meiosis involves a single cell dividing into four haploid cells (each genetically different from one another)
67
Q

Meiosis process

A
  • meiosis I
  • meiosis II
68
Q

explain meiosis I

A
  • copies mitosis
  • separates each homologous chromosome into two different cells (begins with a diploid germline cell and results in two genetically distinct daughter cells)
  • cells will then become the inputs for the second round of division in Meiosis II)
69
Q

meiosis II

A
  • separates each sister chromatid into four different cells (takes haploid cells that were created in Meiosis I, by splitting each of the chromosomes into two sister chromatids, creates four separate haploid cells)
70
Q

Meiosis I sub stages

A
  1. Interphase I
  2. Prophase I
  3. Metaphase I
  4. Anaphase I
  5. Telophase I
71
Q

Meiosis II sub stages

A
  1. Interphase II
  2. Prophase II
  3. Metaphase II
  4. Anaphase II
  5. Telophase II

Bio 1/2 (4 decks)

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