Topic 1 chap 1.3 Biological Molecules 2

Question 1

what are the 3 parts of nucleotides

Answer 1

5 carbon pentose sugar, nitrogen containing base and a phosphate group(PO4 3-)

Question 2

What is the pentose sugar in RNA

Answer 2

ribose

Question 3

what is the pentose sugar in DNA

Answer 3

deoxyribose- fewer oxygen atoms than ribose

Question 4

difference between a purine and a pyrimidine base

Answer 4

purine-2 nitrogen containing rings
pyrimidine- only one nitrogen containing ring

Question 5

name the common purines

Answer 5

adenine and guanine

Question 6

name the common pyrimidines

Answer 6

thymine cytosine and uracil

Question 7

what properties do nucleotides due to the presence of a phosphate group

Answer 7

acidic
negative charge

Question 8

what does ATP stands for

Answer 8

adenosine triphosphate

Question 9

what enzyme catalyses the hydrolysis reaction in which ATP is broken down into a ADP

Answer 9

ATPase

Question 10

what are the products of the hydrolysis of ATP

Answer 10

(ADP) adenosine diphosphate , another nucleotide, a free inorganic phosphate group

Question 11

define what is meant by the term nucleic acid

Answer 11

polymers made up of many nucleotides monomer units that carry all the information needed to form new cells

Question 12

What is a phosphodiester bond

Answer 12

the bond formed between the phosphate group of one nucleotide and the hydroxyl group of the sugar of the next nucleotide in a condensation reaction

Question 13

define the term genome

Answer 13

the entire genetic makeup of an organism

Question 14

how many strands does DNA consist of

Answer 14

2 polynucleotide strands

Question 15

what type of bonds is the DNA double helix held by

Answer 15

hydrogen bonds between complimentary bases

Question 16

what is meant by saying that 2 polynucleotide strands in DNA are antiparallel

Answer 16

Means that they run in opposite directions

Question 17

How many hydrogen bonds formed between guanine and cytosine

Answer 17

3 hydrogen bonds

Question 18

How many hydrogen bonds do adenine and thymine form

Answer 18

2 hydrogen bonds

Question 19

where is energy stored in an ATP molecule

Answer 19

in the bonds between phosphate groups

Question 20

what type of molecule is DNA

Answer 20

polymer

Question 21

how many base pairs for each complete twist of a helix

Answer 21

10 base pairs

Question 22

Outline the process of DNA replication

Answer 22

DNA HELICASE enzyme unwinds and unzips DNA breaking the hydrogen bonds that join base pairs and forming 2 separate strands

DNA polymerase lines up nucleotides along the template strand. Activated (3 PO4 -3 groups instead of 1) free nucleotides line up, only H bonds between complimentary bases at this point
2 extra PO4 -3 lost provides energy for reaction

DNA ligase joins new nucleotides to each other by strong phosphodiester bonds, forming the phosphodiester sugar backbone.

A winding enzyme winds the new strands up to form double helices

The 2 new DNA molecules are identical to the original DNA molecules

Question 23

what do we mean by saying DNA is non overlapping

Answer 23

each base is only part of one triplet/codon, each triplet/codon codes for just one amino acid

Question 24

describe the method of extracting DNA from fruit

Answer 24

+salt to separate cells and begin breaking cell wall
sieve
+detergent breaks cell membrane
+protease uncoils the DNA
to see DNA we must make it soluble so +ice cold ethanol which slows down the action of enzymes.
since ethanol is less dense it forms a layer on the top as DNA precipitates

Question 25

what is a gene

Answer 25

a section of DNA that codes for a sequence of amino acids in a polypeptide chain

Question 26

3 types of RNA

Answer 26

tRNA-transport RNA mRNA-message RNA rRNA- ribosomal RNA

Question 27

where does transcription take place where does translation take place

Answer 27

transcription-nucleus translation-cytoplasm

Question 28

Outline protein synthesis stage 1

Answer 28

Transcription-takes place in the nucleus 1. DNA double helix is separated, 2. mRNA is made using the antisense DNA strand as a template mRNA leaves nucleus and enters cytoplasm

Question 29

outline protein synthesis stage 2

Answer 29

Translation-takes place in the cytoplasm 1.mRNA joins onto a ribosome 2.mRNA acts as a code for tRNA 3. Amino acids on neighbouring tRNA join together 4. a chain of amino acids is formed, we call this a poly-peptide. 5. the polypeptide chain folds to form a protein which is used in the cell or exported to the body. takes place on structures called ribosomes tRNA molecules enable amino acids attached to them to line up in the correct order. the amino acids are joined together by the formation of peptide bonds.

Question 30

what is a polysome

Answer 30

groups of ribosomes joined by a thread of mRNA that can produce large quantities of a particular protein

Question 31

define mutation

Answer 31

a permanent change in the DNA of an organism

Question 32

what are gametes

Answer 32

haploid sex cells produced by meiosis that fuse to form a new diploid cell (zygote) in sexual reproduction

Question 33

what is a point mutation

Answer 33

It is a gene mutation , is a change in one or a small number of nucleotides affecting a single gene.

Question 34

identify and define 3 types of point/gene mutations

Answer 34

deletion -the base is completely lost insertion -an extra base is added into a gene, which may be a repeat or a different base substitution- one base in a gene is substituted for another

Question 35

what are chromosomal mutations

Answer 35

changes in the positions of entire genes within a chromosome

Question 36

what is a whole chromosome mutation

Answer 36

the loss or duplication of a whole chromosome

Question 37

what is sickle cell disease

Answer 37

sickle cell anaemia- human genetic disease affecting the protein chains making up the haemoglobin in red blood cells.

Question 38

what is a mutagen

Answer 38

anything that increases the rate of mutation

Question 39

identify some types of chromosomal mutations

Answer 39

inversions gene deletion gene duplication

Question 40

describe structure of collagen

Answer 40

fibrous proteins with little tertiary structure. triple helix held together by hydrogen bonds, fibrils join together to form collagen fibres long parallel polypeptide chains joined by cross links to form fibres.

Question 41

describe the structure of Haemoglobin

Answer 41

Globular protein 4 polypeptide chains joined by disulphide bonds in a quaternary structure

Question 42

difference between antisense and anticodon

Answer 42

antisense is the strand that codes for proteins while the anticodon is the name given to the sequence of 3 bases on tRNA that correspond to the bases in the mRNA codon.