nucleic acids, atp, water and inorganic ions

Question 1

what does DNA stand for?

Answer 1

deoxyribose nucleic acid

Question 2

function of DNA

Answer 2

codes for seq. of amino acids in primary struc. of protein —> determines tertiary struc. & function of protein

Question 3

shape of DNA polymer

Answer 3

double helix (2 polynucleotide strands)

Question 4

monomer for DNA

Answer 4

nucleotide

Question 5

what does a DNA nucleotide consist of?

Answer 5

-a deoxyribose sugar
-a nitrogenous base (A,T,C,G)
-a phosphate group

Question 6

how is a polynucleotide created?

Answer 6

condensation reactions between deoxyribose of one nucleotide and phosphate group of another

Question 7

what is the bond between a deoxyribose and phosphate group called?

Answer 7

phosphodiester bond (strong cov. bond —> ensures genetic code isn’t broken down)

Question 8

how many h-bonds between c & g?

Answer 8

3

Question 9

how many h-bonds between a & t?

Answer 9

2

Question 10

how does the struc. of DNA relate to the function?

Answer 10

1) sugar-phosphate backbone —> gives it stable struc., protects bases & prevents them from denaturing
2) double stranded —> replication can occur using one strand as template
3) weak h-bonds —> easy unzipping of 2 strands in helix during replication
4) complementary base pairing —> identical copies can be made

Question 11

shape of rna
& what it consists of

Answer 11

• a ribose sugar, a nitrogenous base (A, U, C, G) & a phosphate group
• short, single stranded nucleotide chain

Question 12

function of rna

Answer 12

to copy & transfer the genetic code from dna in the nucleus to the ribosomes

Question 13

what are the diff types of rna?

Answer 13

•mRNA
•tRNA
•rRNA

Question 14

mRNA (messenger rna)

Answer 14

• copy of a gene from a dna strand
• created in nucleus —> leaves nucl. to carry copy of gene to ribosome in cytoplasm

Question 15

shape of mRNA

Answer 15

• single-stranded
• shorted than dna –> allows it to leave the nucleus

Question 16

tRNA (transfer rna)

Answer 16

• only found in cytoplasm
• function —> attaches to a free amino acid & transfers it to the ribosome to create a polypeptide chain
• specific aa’s attach to compl. trna mols —> the 3 trna bases are compl. to the 3 mrna bases —> anticodon compl. to codon

Question 17

shape of tRNA

Answer 17

single-stranded but folded to make a clover-leaf shape

Question 18

rRNA (ribosomal rna)

Answer 18

combines with proteins to form ribosomes

Question 19

diffs between rna & dna

Answer 19

monomers:
* dna has thymine, rna has uracil
* dna has deoxyribose, rna has ribose
polymers:
* dna large, rna short
* dna double stranded, rna single stranded

Question 20

when does dna replication occur?

Answer 20

in interphase, before mitosis/meiosis

Question 21

process of semi-conservative replication

edit using mindmap

Answer 21

1. dna helicase breaks h-bonds between compl. bases in DNA strand
2. double strand separates, 1 strand acts as a template strand
3. free nucleotides join to exposed, compl. bases on template strand
4. phosphate group joined to deoxyribose –> formation of sugar-phosphate backbone catalysed by DNA polymerase

Question 22

evidence for semi-cons. repl.

Answer 22

-bacterial dna replicated in 2 types of nitrogen isotopes (nitrogen found in bases of dna)
-15N = heavy iso. & 14N = light iso.
-dna from 15N would have high density, dna from 14N would have low density
-exp —> 15N bacteria replicated in environment of 14N bacteria —> produces dna mols with half 15N/half 14N —> has medium density

Question 23

what does atp stand for? what is it?

Answer 23

•adenosine triphosphate
•energy carrier mol. (delivers energy for life processes)

Question 24

struc. of atp & how it’s formed

Answer 24

• a ribose sugar, an adenine base & 3 phosphate groups
• formed via a condensation reaction between adp + pi , uses atp synthase enzyme
  (occurs during respiration, energy used)

Question 25

what does adp stand for?

Answer 25

adenosine diphosphate

Question 26

phosphorylation using pi (inorganic phosphate)

Answer 26

* energy can be transferred to other compounds during **hydrolysis** of atp * pi that is released can be **bonded** onto other compounds —> makes them **more** reactive (happens to **glucose** at start of respiration)

Question 27

how does atp release energy?

Answer 27

* carries energy in **bonds** between phosphate groups * **hydrolysis** reaction occurs —> atp = adp + pi (uses **atp hydrolyse** enzyme) * energy **released** from bonds when broken

Question 28

what makes atp a good deliverer of energy?

Answer 28

* **immediate** source of energy —> only needs to break one bond —> bond is weak * **manageable** source —> releases **small** amount of energy

Question 29

uses of atp in organisms (name 3!)

Answer 29

•protein synthesis •dna replication •cell division •active transport •maintaining constant body temp (homeostasis) •metabolic reactions

Question 30

which types of bonds form between water molecules?

Answer 30

h-bonds

Question 31

properties of water n how they make water important for biological processes

Answer 31

1) water = **metabolite** eg. hydrolysis/photosynthesis 2) water = important **solvent** in reactions —> transports things with ease eg. substances in plasma in blood/substances in water in xylem 3) **high** heat capacity —> **buffers** temps —> enzymes in body wont denature easily 4) **large** latent heat of vaporisation —> provides **cooling** effect with loss of water through evaporation 5) strong **cohesion** between water mols (due to h-bonds between mols) —> supports columns of water being pulled up xylem —> also produces surface tension to support small organisms

Question 32

inorganic ions

Answer 32

•found in solutions eg. in cytoplasm & body fluids of organisms •don’t contain carbon

Question 33

H+ ions

Answer 33

•higher H+ conc. = lower pH •pH affects enzyme controlled reactions

Question 34

Fe2+ ions

Answer 34

•haemoglobin made from 4 poplypeptide chains, each with Fe2+ bound to prosthetic haem group in centre •Fe2+ temporarily binds to oxygen, making Fe3+ until the oxygen is released

Question 35

Na+ ions

Answer 35

•used for co-transport of glucose/amino acids into cells —> sodium moved out by active transport… •affects osmosis/w.p

Question 36

phosphate ions

Answer 36

•found in dna (form phosphodiester bonds with deoxyribose sugar) •used to produce atp •phosphorylates other compounds, making them more reactive

Question 37

diff. between prokaryotic dna & eukaryotic dna

Answer 37

*prokaryotic dna = non-linear, eukaryotic dna = linear *prokaryotic dna has no histone proteins, eukaryotic dna has histones

Question 38

how do organisms have the same bases but different. shapes n functions?

Answer 38

* organisms have **diff. genes** * the **bases** are sequenced in a diff. order * the diff. a.a sequences **code** for diff. proteins

Question 39

why does the tissue being viewed under a microscope need to be thin?

Answer 39

>so more light can go through >a single layer of cells can be viewed

Question 40

when a dna strand is being produced via scr, why do the enzymes work in opposite directions?

Answer 40

* dna has **anti-parallel** strands * the nucleotides are **aligned** differently in both strands * enzymes have actives sites with **specific** shapes * only substrates with compl. shape can bind to active site of dna polymerase

Question 41

why is a certain virus only found in a certain part of the body?

Answer 41

* outside of virus has antigen proteins * antigen proteins have compl. shape to **receptor** protein * receptor proteins only found on **membrane** of cell