Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

a level > B2 > Flashcards

B2 Flashcards

(49 cards)

Start Studying
1
Q

nucleotide structure

A

pentose sugar
phosphate group
nitrogenous organic bases

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

how are nucleotides joined

A

condensation reaction
phosphodiester bond (covalent)

mononucleotide–>dinucleotide–>polynucleotide

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

RNA structure

A

ribose pentose sugar
A, U, G, C

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

RNA uses

A
  • mrna: synthesised in transcription- transfers genetic info from nucleus - cytoplasm + ribosomes
  • trna: bring amino acids to ribosome complementary to mrna codon to form polypeptide in protein synthesis
  • ribosomes = made of protein + rna
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

DNA structure

A

pentose sugar = deoxyribose
A, T, G, C
two strands = antiparallel
double helix
hydrogen bonds between complementary base pairs
phosphodiester bonds joining nucleotides together

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

stability of DNA

A
  • phosphodiester backbone protects the more chemicallly reactive organic bases inside double helix
  • hydrogen bonds link organic bases
    3 hydrogen bonds between cytosine and guanine- more of these…more stable
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

function of DNA

A

hereditary molecule responsible for passing genetic information from cell to cell and generation to generation

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

how is DNA adapted to carry out its functions

A

very stable structure- passes between generations without significant changes

2 separate strands = joined with weak hydrogen bonds, allows them to separate during DNA replication and protein synthesis

extremely large molecule- carries immense amount of info

base pairing- DNA is able to replicate easily and transfer info as mRNA

4 different nitrogenous bases- ability to code information

each strand acts as a template at the same time

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

2 main stages of cell division

A

nuclear division
- can be mitosis or meiosis

cytokinesis
- followed by nuclear division- whole cell divides

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

why must DNA be replicated before a cell divides

A

to ensure all daughter cells have the genetic information to produce the enzymes and other proteins they need

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

requirements for semi-conservative replication

A
  • 4 types of nucleotide
  • both DNA strands to act as template
  • DNA polymerase
  • source of chemical energy
  • hydrogen bonds
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

how the structure of DNA enables semi conservative replication

A
  • double stranded
  • weak hydrogen bonds
  • complementary bases
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

DNA replication

A
  • DNA helicase unwinds the double helix
  • hydrogen bonds between complementary bases = broken
  • each strand acts as a template
  • new/free nucleotides form complementary base pairs
  • A+T, G+C
  • DNA polymerase forms covalent bonds between pentose and phosphate
    forms phosphodiester bonds between nucleotides
  • process continues along entire molecule
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

conservative model of DNA replication

A
  • the original DNA molecule remains intact
  • a separate daughter DNA copy is built from new molecules of deoxyribose, phosphate and organic bases
  • of the 2 molecules produced, 1= entirely new and 1= entirely original
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

semi-conservative model of DNA replication

A
  • original DNA molecule = split into two separate strands
  • each strand replicates w complementary base pairing
  • each of the 2 new molecules has 1 original and 1 new strand
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

why is the direction of DNA polymerase in opposite directions?

A
  • DNA has antiparallel strands
  • the shape of adjacent nucleotides are different
  • enzymes have an active site with a specific shape
  • only substrates with a complementary shape will bind to the active site of DNA polymerase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

structure of ATP

A

a phosphorylated macromolecule

  • adenine: nitrogenous organic base
  • ribose: pentose sugar that acts as a backbone
  • phosphates: chain of 3 phosphate groups
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

how ATP stores energy

A
  • bonds between phosphate groups = unstable w/ low activation energy so easily broken
    when they do break, they release lots of energy

ATP + H2O –> ADP +Pi + (energy released for use by cells)

  • catalysed by ATP hydrolase (ATPase) in hydrolysis
  • exothermic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

synthesis of ADP

A

energy = used to add an inorganic phosphate to ADP to re-form ATP

ADP + Pi + (energy supplied from respiration) –> ATP + H2O

  • catalysed by ATP synthase
  • condensation
  • endothermic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

the 3 ways in which synthesis of ATP occurs

Study These Flashcards
A
  • photophosphorylation
    in chlorophyll-containing plant cells during photosynthesis
    energy = from sunlight
  • oxidative phosphorylation
    in plant and animal cells during respiration
    energy = from electrons from oxidising of glucose
  • substrate-level phosphorylation
    in plant and animal cells when phosphate groups are transferred from donor molecules to ADP
    by enzymes
21
Q

roles of ATP

Study These Flashcards
A

good energy donor- not a good long term energy store
–> due to instability of its phosphate bonds
- immediate energy source of cell
so cells don’t store large quantities of ATP , just a few seconds supply
but it can be rapidly made again

22
Q

why is ATP a better immediate energy source than glucose

Study These Flashcards
A

energy = released in smaller, manageable amounts
hydrolysis = single reaction that releases immediate energy
phosphorylates other molecules, lowering their activation energy

23
Q

ATP is useful in many biological processes. explain why

Study These Flashcards
A
  • releases energy in small/manageable amounts
  • broken down in one step
  • immediate energy source so energy = readily available
  • phosphorylates other compounds
  • lowering their activation energy, making them more reactive
  • can be reformed/ made again
24
Q

why do we need to make ATP continuously

Study These Flashcards
A

ATP cannot be stored
it can move around a cell freely (it is soluble)
cannot cross the cell membrane- polar + no protein carriers
has to be continuously made within the mitochondria of cells that need it

25
why can ATP not cross the cell membrane
it is polar it has no protein carriers
26
uses of ATP
a METABOLITE provides the energy in metabolic processes needed to build up macro-molecules from their basic units MOVEMENT provides the energy for muscle contraction for muscle filaments to slide past each other and so shorten the overall length of the muscle fibre ACTIVE TRANSPORT provides the energy needed to change the shape of carrier proteins in plasma membranes so molecules/ ions can move against a concentration gradient SECRETION needed to form the lysosomes necessary for secretion of cell products ACTIVATION OF MOLECULES the inorganic phosphate released during hydrolysis of ATP can be used to phosphorylate other compounds to make them more reactive, lowering their activation energy in enzyme-catalysed reactions
27
describe how an ATP molecule is formed from its component molecules
adenine, ribose sugar, 3 phosphates joined by condensation reaction by ATP synthase during respiration / photosynthesis
28
give two ways in which the hydrolysis of ATP is used in cells
phosphorylates other molecules to make them more reactive releases energy during respiration
29
the dipolar water molecule
O has 8- H has 8+ dipolar forms hydrogen bonds causes water molecules to stick together
30
high specific heat capacity of water
because water molecules stick together, it takes more energy to separate them so bp is higher than expected it takes more energy to heat a given mass of water water therefore acts as a buffer against sudden temperature changes, making the aquatic environment a temperature-stable one
31
high latent heat of variation
hydrogen bonding between water molecules means it requires lots of energy to evaporate 1g of water evaporation of water such as sweat in mammals is therefore a very effective means of cooling because body heat is used to evaporate the water.
32
cohesion and surface tension in water
cohesion: the tendency of water molecules to stick together - with its hydrogen bonding, water has large cohesive forces that allow it to be pulled up through a tube e.g. xylem in transpiration stream - in the same way, where water molecules meet air they tend to be pulled back into the body of water rather than escaping from it at an air-water surface, the cohesion between water molecules produces surface tension, creating a solid-like surface
33
water in metabolism
- water is used to break down many complex molecules by hydrolysis e.g. proteins to amino acids - water is also produced in condensation reactions - chemical reactions take place in an aqueous medium - water is a major raw material in photosynthesis
34
water as a solvent
water readily dissolves other substances: - gases e.g. O2 CO2 - waste e.g. ammonia and urea - inorganic ions and small hydrophillic molecules e.g. amino acids, monosaccharides, ATP - enzymes, whose reactions take place in solution
35
other important features of water
its evaporation cools organisms and allows them to control their temperature it is not easily compressed, so provides support e.g. hydrostatic skeleton of earthwork and turgor pressure in plants it is transparent and therefore aquatic plants can photosynthesise light rays can penetrate the jelly-like fluid that fills the eye and so reach the retina
36
where are inorganic ions found
in solution in the cytoplasm of cells in bodily fluids part of larger molecules
37
role of iron ions
found in haemoglobin, play a role in transport of O2
38
role of phosphate ions
form a structural role in DNA store energy in ATP structural in phospholipid bilayer
39
role of H+
determine the pH of solutions and therefore the functioning of enzymes
40
role of Na+
important in transport of glucose and amino acids across plasma membranes Na K pump
41
roles of NH3
amino acids nitrogenous bases
42
role of Ca+
muscle contraction
43
explain the properties of water that make it important for organisms
METABOLITE in condensation/hydrolysis/photosynthesis/respiration SOLVENT a universal solvent- only for polar substances so metabolic reactions can occur HIGH SPECIFIC HEAT CAPACITY so temperature buffer LARGE LATENT HEAT OF VAPORISATION providing cooling effect through evaporation COHESION BETWEEN WATER MOLECULES so provides support to columns of water in plants COHESION between water molecules produces surface tension, supporting small organisms
44
properties of water that are important in the cytoplasm of cells
polar molecule acts as a universal solvent metabolic reactions occur faster in solution very reactive metabolic reactions occur efficiently temperature buffer- high specific heat capacity maintains optimum temp for enzymes
45
describe the structure of DNA (5)
- a polynucleotide - each nucleotide formed from deoxyribose, phosphate group, and nitrogenous base - phosphodiester bond between nucleotides - double helix structure - hydrogen bonding between adenine + thymine and guanine + cytosine
46
describe how a phosphodiester bond is formed between two nucleotides (3)
- condensation reaction - between phosphate and deoxyribose - catalysed by DNA polymerase
47
describe the role of DNA polymerase in the semi-conservative replication of DNA (3)
- joins adjacent DNA nucleotides - catalyses condensation reactions - catalyses the formation of phosphodiester bonds between adjacent nucleotides.
48
describe the role of two named enzymes in the process of semi-conservative DNA replication
DNA helicase causes breaking of hydrogen bonds between bases on DNA strands DNA polymerase joins DNA nucleotides forming phosphodiester bonds
49
describe the role of iron, sodium and phosphate ions in cells
iron haemoglobin binds with O2 in RBC sodium co-transport of glucose/amino acids because sodium moves out by active transport by Na-K pump creates a concentration gradient phosphate used to produce ATP phosphorylates other compounds, making them more reactive part of phospholipid bilayer

a level (29 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions