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Biology > Biological Molecules B > Flashcards

Biological Molecules B Flashcards

1
Q

What are nucleotides made up of?

A

Pentose sugar
Nitrogen containing organic base
Phosphate group

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2
Q

DNA bases and sugar
what makes each nucleotide different?

A

Pentose sugar- deoxyribose
Bases- adenine, thymine, cytosine, guanine
Each DNA nucleotide has same sugar and phosphate but diff bases

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3
Q

Bases and sugar in rna

A

Penrose sugar- ribose
Bases- adenine, uracil, cytosine, guanine
Each nucleotide same apart from bases

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4
Q

What is a polynucleotide?
How does it form?

A

Polymer of nucleotides eg DNA
Join via condensation reaction between phosphate of one and sugar of another forming phosphodiester bond- sugar phosphate backbone

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5
Q

DNA structure

A

2 polynucleotide chains joined by H bonds between bases
Complimentary base pairing- A,T(2 H bonds) G,C(3 H bonds)
2 anti parallel stands form double helix

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6
Q

Pyramidines and purines

A

Pyramidines- T and C, single ringed
Purines- A and G, double ringed
Pyramidines join to purines

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7
Q

When was DNA discovered?

A

First in 1800s but doubted it carried whole genetic code
1953- proved it did
1953- Watson and Crick discovered double helix

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8
Q

RNA structure

A

Single polynucleotide chain
Shorter than DNA polynucleotide

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9
Q

Properties of DNA

A

Stable- backbone protects chemically reactive organic bases in double helix
3 H bonds c-g so more c-g means more stable
Diverse- infinite variety- 3.2 bill base pairings

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10
Q

DNA adapted to function

A

Stable- doesn’t mutate when passes to generations
Stands joined by H bond so can separate
Large- carries lots of info
Bases protected by backbone
Base pairing means it can replicate and transfer info as mRNA

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11
Q

Semi-conservative replication process

A

1) DNA helicase breaks H bonds between bases so unwinds forming 2 single strands
2) each og strand acts as template for new one. free floating nucleotides attach to complimentary exposed bases on template strands
3) condensation reaction joins nucleotides together catalysed by DNA polymerase. H bonds form between bases on new and old strands’
4) each new DNA molecule has 1 strand of og DNA molecule and one of new

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12
Q

4 requirements for semiconservative DNA replication

A

1) 4 types of nucleotide w bases present
2) both strands act as template for attachment of nucleotides
3) dna polymerase present
4) source of chem energy required

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13
Q

what does antiparallel mean?

A

dna strands run in opposite directions

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14
Q

which way does dna polymerase work?

A

3’-5’ of the template strand so nucleotides added from 3’ of the template strand as active site of polymerase compliments 3’

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15
Q

which direction is the new strand made in?

A

5’-3’

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16
Q

which carbon does phosphate attach to?
which carbon does hydroxyl attach to?

A

5’
3’

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17
Q

does dna polymerase run in the same direction or opposite on each strand?

A

opposite

18
Q

meselson and stahl’s experiment

A

1) 2 bacteria samples grown. 1 in broth w 14N other w 15N. bacteria reproduce taking up N from broth to help make nucleotides so becomes part of DNA
2) sample of dna taken from each batch and centrifuged. dna from heavy N settled lower
3) bacteria in heavy n put in light broth. replicated once and centrifuged
4)if conservative, og heavy would settle at bottom and light at top
5) if semi, would contain 1 old and 1 new strand so would settle in middle
6) it did settle in middle showing it contained 14N and 15N

19
Q

why is water vital to living organisms?

A

about 80% of cells contents
important metabolite in hydrolysis etc
solvent- most metabolic processes happen in solutions
very cohesive- helps water transport in plants etc

20
Q

does water have a high or low latent heat of vaporisation and specific heat capacity? advantages of this?

A

high
helps control body temperature

21
Q

is water polar or not? why?

A

polar
h positive as electrons pulled more to o
o negative as unshared electrons
allows hydrogen bonding

22
Q

6 useful properties of water

A

. metabolite- many metabolic reactions involve condensation
. high latent heat of vaporisation- lots of energy to break h bonds so lots needed to vaporise so can use water loss through evaporation to cool down wo losing too much water
. can resist changes in temp- h bonds absorb lots energy so high spec heat cap so no rapid temp changes
. good solvent- water polar so can surround ionic structures and dissolve them
. not easily compressed- supportive eg hydro-elastic skeleton in worms and turgor in plants
. transparent- aquatic plants can photosynthesise, light can penetrate fluid in eyes to reach retina

23
Q

what is cohesion?
why are water molecules so cohesive and benefits?

A

attraction between molecules of the same type/ tendency of molecules to stick together
because theyre polar
helps water flow- transporting substances up xylem

24
Q

surface tension

A

water has high surface tension when in contact w air as it is cohesive- water molecules pulled back into body of water

25
Q

what is capillary action?

A

water adheres to walls of column and moves upwards. narrower= moves further up as pull from meniscus overcomes mass of water in tube- smaller mass in smaller tube

26
Q

6 reasons why is energy important?

A

metabolic processes
movement/ muscle contractions
active transport- change shape of carrier proteins
secretion- form lysosomes needed
activating molecules
dna replication and cell division

27
Q

structure of ATP

A

energy released from glucose in respiration used to make ATP
made of adenine (the DNA base), ribose sugar and 3 phosphate groups
nucleotide derivative

28
Q

where is energy stored in ATP? how is it released?

A

high energy bonds (unstable so little activation energy to break) between phosphate groups
released in hydrolysis

29
Q

equation for break down on ATP
catalyst?

A

ATP-> ADP + Pi
ATP hydrolase

30
Q

what is phosphorylation?

A

Pi added to other compounds making them more reactive
phosphorylation- photosynthesis
oxidative phosphorylation- respiration
substrate level phosphorylation

31
Q

resynthesis of ATP equation and catalyst

A

ADP+ Pi -> ATP
ATP synthase
happens in respiration and photosynthesis

32
Q

ATP vs glucose

A

ATP is glucose in 38 parts- releases less energy so more manageable amount
quicker as glucose takes longer to breakdown
ATP is immediate
but cant be stored- constantly being made in mitochondria of cells that need it

33
Q

Iron ions

A

in haemoglobin which is 4 diff polypeptide chains with Fe2+ in centre
Fe2+ binds to O2 to temporarily become Fe3+

33
Q

What is an inorganic ion?

A

atom with a charge that doesnt contain carbon

34
Q

Hydrogen ions

A

determines pH which is a measure of conc of H+
more H+ is more acidic and lower pH
enzyme controlled reactions are affected by pH

35
Q

Sodium ions

A

glucose and amino acids need help crossing cell membranes
can be transported across in cotransport alongside Na+

36
Q

Phosphate ions

A

Phosphate ion attached to other molecules creates phosphate group
ATP, DNA, RNA all contain phosphate groups
bond between store energy in ATP
in DNA and RNA, join so allow nucleotides to form polynucleotides

37
Q

Advantage of hydrolysis of ATP being coupled to energy-requiring reactions within cells.

A

energy released can be directly used to make coupled reaction happen rather than being lost as heat

38
Q

Where can you find inorganic ions?

A

Cytoplasm of cells and bodily fluids of organisms

39
Q

Role of RNA

A

Transfers genetic info from DNA to ribosomes

Biology (10 decks)

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