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Year 12 Bio > 1.3 and 1.4 bio mols 2 and enzymes > Flashcards

1.3 and 1.4 bio mols 2 and enzymes Flashcards

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1
Q

bases can either be purine or pyrimidine which are attracted by hydrogen bonds , what are they?

A

purine - 2 nitrogen containing rings. adenine, guanine in rna and DNA

pyrimidine -1 nitrogen containing rings
-thymine, cytosine in DNA
- uracil and cytosine in RNA

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2
Q

what is atp?

A

a nucleotide which is a universal energy supply molecule

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3
Q

how does atp release energy?

A

in a hydrolysis reaction the 3rd phosphate bond is broken, this is catalysed by ATPase enzyme, ADP is the product

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4
Q

nucleic acid?

A

-polymers consisting of nucleotide monomers that carry info to make new cells

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5
Q

whats a phosphodiester bond in dna?

A

bond formed between phosphate mol in one nucleotide and the sugar of another nucleotide in a condensation reaction

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6
Q

how is DNA replicated? (Semi conservative)

A
  1. enzyme DNA helicase unzips the DNA molecule by breaking through hydrogen bonds
  2. Nucleotides line up along strands by complimentary base pairing
  3. DNA polymerase joins adjacent nucleotides catalysing condensation reactions, and forming pdb
  4. dna ligase joins sections of dna together, forming phosphodiester bonds. between sug and phosphates
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7
Q

define a gene

A

sequence of bases on a DNA molecule coding for a sequence of amino acids in a polypeptide chain

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8
Q

whats a codon/triplet

A

sequence of 3 bases of mRNA

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9
Q

the genetic code is degenerate , give an adv

A

degenerate - more than one triplet can code for the same amino acid
adv - mutations occur triplets can may code for same aa. Helps maintain same protein structure

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10
Q

triplet code is non - overlapping…

A

each triplet is read separately

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11
Q

describe steps of transcription

A
  1. DNA molecule unzips, separating dna strands
  2. complimentary RNA nucleotides attach to template strand
  3. phosphodiester bonds form in condensation reactions
  4. rna polymerase
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12
Q

describe steps of translation

A
  1. ribosome attaches to mRNA
  2. At each codon a molecule of tRNA with complimentary anticodons line up.
  3. each tRNA carries specific amino acid
  4. amino acid joined by peptide bonds formed in condensation reactions
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13
Q

what is the structure of enzymes ?

A

globular proteins

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14
Q

explain enzyme specificity..

A

enzymes have specific shapes resulting from their tertiary and quaternary structures
-bc of this they only catalyse specific reactions

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15
Q

enzymes can catalyse ..

A

intracellular reactions (reactions within cell)
extracellular reactions (reactions outside cell)

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16
Q

What takes place in mutation substitution and silent

A
  1. Base changes in dna
  2. Mrna transcribes a diff codon
  3. Codon codes for diff aa making a diff polypeptide as it’ll fold In a diff way
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17
Q

What takes place in mutation deletion

A
  1. Base deleted from dna, frame shift occurs
  2. All codons diff, all aa diff, polypeptide folds differently
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18
Q

What’s a mutation

A

Changes to a base sequence such as base deletions , insertions or substitutions

19
Q

Enzymes are biological catalysts

A

That speed up the rate of reaction by lowering the activation energy required

20
Q

Induced fit hypothesis?

A

Active site has distinct shape but is flexible.
Once substrate enters active site the shape of the site modifies around it forming active complex

21
Q

state the importance of miosis

A

they result in genetic variation thru independent assortment and crossing over
-halves chromosome number to produce haploid nuc so at fertalistion the no of chromosomes is restored

22
Q

2 types of genetic variation in miosis

A

crossing over (recombination) - the exchange of sections of DNA between homologous chromosomes.

independent assortment - where the chromosomes derived from female and male parent are distributed into the gametes at random

23
Q

what are chromosome mutations ?

translocation?

A

during meiosis parts of the chromosomes break off and are reattached in the wrong place

a type of cm where part of a chromosomes breaks off and joins to another chormosme

24
Q

what is non disjunction error?

A

pair of chromosomes fail to separate, during division of meiosis, resulting in one gamete w 2 copies of the chromsome and one gam with 0 copies

25
Q

how can non disjunction lead to polysomy?
whats an example?

A

one gamete has 2 copies of the chromosome, after fertilisation with a normal gamete , the zygote will have polysomy (3 chro)
down syndrome

26
Q

how can non disjunction lead to monosomy?

A

only one member of a pair of chromosomes is present in a cell

27
Q

what is competitive inhibition? reversible

A

when the substrate and inhibitor molecule have similar shapes to each other and both compete for the enzyme active site. preventing sub entering

28
Q

what is non competitive inhibition? reversible

A

when the inhibitor molecule binds to the allosteric site / away from as changes the shape of the active site so it cant catalyse reactions

29
Q

why is enzyme inhibition important ?
what is end product inhibition?

A

to regulate metabolic pathways
when the amount of end product is high it binds non competitively to an enzyme in the pathway blocking further production

30
Q

what is spermatogenesis ?
what is oogenesis?

A

the creation of spermatozoa by primordial germ cells in the testes

the creation of ova by primordial germ cells in the ovary

31
Q

what happens in oogenesis?

A
  1. primary diploid ococyte divides by miosis to produce a big secondary haploid oocyte and a smaller polar body
  2. secondary ooctye divids to produce haploid ovum and another polar body. the first polar body divides to produce 2 more
32
Q

what happens in spermatogenesis?

A

the primary diploid spermatocyte divides by miosis into 2 haploid cells called secondary spermatocytes
-these each divide again so there are 4 haploid cells called spermatids
-spermatids differentiate to produce sperm, which includes an acrosome etc.

33
Q

adv of sperm cells

A

contain flagellum to allow the cell to move

34
Q

summarise fertalisation

A
  1. sperm cluster around 2nd oocyte
  2. one sperm head touches surface , acrosome reaction triggered
  3. enzymes are released by many sperm , which digest the follicle cells and jelly layer
  4. head of one sperm fuses w oocyte membrane, enters cell, tail left behind
  5. head absorbs water, bursts releasing chromosomes to fuse w ovums

second mietoic divisio triggered after fertalisation

35
Q

prevention of polyspermy?

A

sperm cell fuses w egg cell membrane
cortical granuels fuse with egg cell membrane
-exyocytosis of cortical granuels happen and contents they contain are released into jelly layer of egg cell
-protease enzymes cause jelly layer to thicken, fertalisation membrane

36
Q

Explain the role of the active site in the conversion of succinate to fumarate (exam q )

A

-Active site has a specific shape to fit the specific substrate succinate
-lowers a.e
-double bond forms between carbons
- esc formed

37
Q

Explain the effect of ph on enzyme activity

A
  • change in pH affect the interactions between r groups
38
Q

after fertalisation what happens

A

cleavage - mitosis without interphase
blastocyst - undifferentiated ball of cells
in the embryo each cell can produce any tissue

39
Q

draw out male and female gametogenesis in plants

A

.

40
Q

in male gametogenesis in plants what are the functions of the tube and generative nuclei

A

tube - has function of producing a pollen tube, which penetrates thru the ovary and down to the ovule
g - divides by mitosis in the pollen tube , one of these then fuse w egg cell nucl to form offspring

41
Q

fertilisation in plants..

A

pollen grain lands on stigma.
pollen tube grows from pollen grain and grows to the ovary (ovary is where embryo female sac is)
-generative nucleus travels down it
-g.n divides by mitosis to from 2 male nuclei

42
Q

fertlisation in plants p2

A

pollen tube fuses with embryo sac
double fertalisation takes place
one male nuc fuses w egg cell nuleus to produce diploid zygote
other male nuc fuses w 2 polar nuclei to produce triploid endosperm nucleus

43
Q

how is tube growth achieved in plants?

A

by the production of enzymes which digest the tissue of the style making a hollow tube

Year 12 Bio (5 decks)

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