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Biology > Mod 5: Heredity - Cell Replication > Flashcards

Mod 5: Heredity - Cell Replication Flashcards

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1
Q

what is heredity

A

how traits are passed down

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2
Q

what are traits

A

things that are encoded within DNA

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3
Q

what are the nitrogenous bases in DNA

A

adenine, thymine, cutosine, guanine

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4
Q

what are the nitrogenous bases in RNA

A

adenine, uracil, cytosine, guanine

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5
Q

what are chromosomes

A

compacted DNA wrapped around protein structures (histones)

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6
Q

what does DNA stand for

A

deoxyribonucleic acid

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7
Q

what are genes

A

sections of DNA coiled around a protein

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8
Q

what is part of the DNA structure

A
  • anti-parallel dna strands
  • ladder structure
  • double helix
  • millions of nucleotides
  • sugar-phosphate backbone
  • 5’-3’ and 3’-5’ directions
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9
Q

who discovered DNA

A

watson, crick and franklin

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10
Q

where is DNA found in prokaryotes

A

circular DNA within the nucleoid and in small rings of plasmids

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11
Q

where is DNA found in eukaryotes

A

linear chromosomes within the nucleus and in mitochrondria and chloroplasts

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12
Q

what happens before cells divide

A

interphase - dna must be replicated first

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13
Q

what phases are in interphase in mitosis

A

G1, S, G2, mitosis
G1 is growth
S is DNA synthesis
G2 is growth and preparation for mitosis
Mitosis is PMAT

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14
Q

what happens during interphase

A

cell will be growing and DNA will go through the process of DNA replication

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15
Q

why is it important for DNA replication to occur in cells

A
  • New cells has identical genetic information
  • Required to have same information of structure and function
  • Syllabus: continuity of species - making sure there are no faults within the DNA
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16
Q

what enzymes are involved in DNA replication

A

helicase, DNA polymerase, primase, ligase

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17
Q

what does helicase do

A
  • also known as the unzipper
  • separates the two DNA strands into separate DNA strands
  • breaks apart the hydrogen bonds
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18
Q

what does DNA polymerase do

A
  • also known as the builder
  • builds a complementary strand to the now separate DNA strands
  • has bias - only builds in the 5’ - 3’ direction
  • builds the leading strand continuously as it is in favour
  • builds the lagging strand in fragments (Okazaki fragments) - continous priemrs throughout the strand
  • another type of polymerase replaces the RNA primers with DNA nucelotides
  • a different type of polymerase reads through all the new DNA and fixes any errors
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19
Q

what does primase do

A
  • also known as initialiser
  • made of RNA
  • the starting block for polymerase to begin
  • leading strand only has one
  • lagging strand has primers all along as polymerase cannot build a continuous strand
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20
Q

what does ligase do

A
  • also known as gluer
  • seals the DNA
  • sticks together the Okazaki fragments together on lagging strand
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21
Q

what do the single-stranded binding (SSB) proteins do

A
  • binds to the strands after the unzipping to ensure that there is no reconnection until after DNA is replicated
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22
Q

what does topiomerase do

A
  • attaches to the DNA to prevent supercoiling
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23
Q

what are the different models of DNA

A

conservative
semi-conservative
dispersive

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24
Q

what is the conservative model

A

DNA would be copied and made an identical second new molecule

25
Q

what is the dispersive model

A

the DNA gets cut up into pieces and gets copied separately before being reattached with segements of botht the new and parent DNA in both strands

26
Q

what is the semi-conservative model

A

the two DNA strands separate and each strand serves as a template to make two new strands and the result is one original strand and one new strand in both the DNA molecules

27
Q

what are two aspects of DNA replication in regards to continuity of species

A
  • genetic stability
  • genetic variation
28
Q

why genetic stability is good

A

producing identical DNA strands enables favourable traits to be passed on
* somatic - enables them to function correctly and keep organism alive to reproduce
* gametes - enables favourable traits to be passed to the next generation

29
Q

why genetic variation is good

A

low levels of mutation are introduced - low variation
* natural selection can occur and specieis is more likely to survive changes

30
Q

what is mitosis

A

the process of where one parent cell divides into two identical daughter cells with the same number of daughter cells

31
Q

what is mitosis used for

A

for somatic (body) cells for growth and repair - repair of damaged tissue and replacement of old cells

32
Q

genetic stability in mitosis

A

ensures the precise and equal distrubution of chromosomes to each daughter cell resulting in all daughter cells having the same chromosome number and genetic information

33
Q

what cells fo mitosis produce

A

body cells

34
Q

how many chromosomes are in humans

A

46 in body cells
23 in gametes

35
Q

how many chromatids are in a cell

A

92 chromatids in body cells
46 chromatids in gametes

36
Q

do cells divide all the time

A

no, because uncontrolled cell growth can lead to cancer and cells are programmed to know when to start and stop

37
Q

how long is interphase and mitosis in the cell cycle

A

interphase - 90%
mitosis/cell division - 10%

38
Q

what the stages of division in mitosis

A

I - interphase
P - prophase
M - metaphase
A - anaphase
T - telophase
C - cytokinesis

39
Q

what happens in interphase (mitosis)

A
  • cell replication occurs
  • all the genetic information (DNA) gets duplicated
40
Q

what happens in prophase (mitosis)

A
  • chromatin (loose DNA) condenses into chromosomes
  • chromosomes have two copies of DNA, one copy in each chromatid
  • mitotic spindle fibre begin to form and extend across the cell
41
Q

what happens in metaphase (mitosis)

A
  • centrioles duplicate and spindle fibres form
  • chromosomes line up at ‘equator’ each attached to a mitotic spindle fibre at the centromere
  • at this point, chromsomes still have two chromatids
42
Q

what happens in anaphase (mitosis)

A
  • centromere is cleaved, allowing sister chromatids to be separated
  • each chromatid is not a separate chromosome
  • mitotic spindle fibres contract and chromosomes are pulled apart to opposite ends of the pole
42
Q

what happens in telophase (mitosis)

A
  • duaghter chromosomes gather at opposite ends
  • mitotic spindles break down
  • nucleur membrane begins to assemble
  • result of two identical nuclei with chromosomes identical to one another
43
Q

what happens in cytokinesis (mitosis)

A
  • final separation into two cells by splitting cytoplasm
  • nucleur division is complete and cell ccycle renews itself
44
Q

what is meiosis

A

a type of cell division where a parent cell divides into 4 unique daughter cells

45
Q

where does meosis occur

A

in sex cells (gametes)

46
Q

how many rounds of nuclear divison is in meiosis

A

2 - I PMATx2 C

47
Q

why do some cells have 46 and some have 23

A

reduction division

48
Q

what are the different types of genetic variation methods of meiosis

A
  • crossing over
  • independent assortment
  • random segregation
49
Q

what happens in interphase (meiosis)

A
  • same as mitosis
  • DNA as chromatin is duplicated
  • cell is growing and getting ready for division
50
Q

what happens in prophase I (meiosis)

A
  • chromosomes duplicate, condense, thicken and line up in homologous pairs
  • crossing over occurs –> ensures genetic variation and that the inferitance is a mix of maternal and paternal genes
51
Q

what happens in metaphase I (meiosis)

A
  • independent assortment occurs - law of independent assortment states that the allele of one gene separates idependently of an allele of another gene –> random nature of separation of maternal and paternal chromosomes into daughter cells (even split into all cells) —> genetic variation
  • homologous chromosmes pairs line up in equatoria plate in two lines
52
Q

what happens in anaphase I (meiosis)

A
  • homologous pairs are pulled away by spindle fibres
  • random segregation occurs - chromosomes are randomly allocated tot eh new daughter cells
53
Q

what happens in telophase I (meiosis)

A
  • nuclear membrance assembles around the chromosomes
  • cytokinsis occurs to split the cell to produce 2 different daughter cells
54
Q

what happens in prophase II (meiosis)

A
  • chromosomes and spindles form in prophase II
  • there is no crossing over
55
Q

what happens in metaphase II (meiosis)

A
  • chromosomes line up inthe middle in single file
56
Q

what happens in anaphase II (meiosis)

A
  • chromatids get pulled away by spingle fibres to opposite sides
  • chromosomes again unergo random segregation and are randomly allocated to each new daughter cell –> law of segregation states that the two alleles of a single trait will separate randomly, meaning that there is a 50% either allele will end up in either gamete
57
Q
A

Biology (8 decks)

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