Topic 1 chap 1.3 Biological Molecules 2 Flashcards
what are the 3 parts of nucleotides
5 carbon pentose sugar, nitrogen containing base and a phosphate group(PO4 3-)
What is the pentose sugar in RNA
ribose
what is the pentose sugar in DNA
deoxyribose- fewer oxygen atoms than ribose
difference between a purine and a pyrimidine base
purine-2 nitrogen containing rings
pyrimidine- only one nitrogen containing ring
name the common purines
adenine and guanine
name the common pyrimidines
thymine cytosine and uracil
what properties do nucleotides due to the presence of a phosphate group
acidic
negative charge
what does ATP stands for
adenosine triphosphate
what enzyme catalyses the hydrolysis reaction in which ATP is broken down into a ADP
ATPase
what are the products of the hydrolysis of ATP
(ADP) adenosine diphosphate , another nucleotide, a free inorganic phosphate group
define what is meant by the term nucleic acid
polymers made up of many nucleotides monomer units that carry all the information needed to form new cells
What is a phosphodiester bond
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
define the term genome
the entire genetic makeup of an organism
how many strands does DNA consist of
2 polynucleotide strands
what type of bonds is the DNA double helix held by
hydrogen bonds between complimentary bases
what is meant by saying that 2 polynucleotide strands in DNA are antiparallel
Means that they run in opposite directions
How many hydrogen bonds formed between guanine and cytosine
3 hydrogen bonds
How many hydrogen bonds do adenine and thymine form
2 hydrogen bonds
where is energy stored in an ATP molecule
in the bonds between phosphate groups
what type of molecule is DNA
polymer
how many base pairs for each complete twist of a helix
10 base pairs
Outline the process of DNA replication
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
what do we mean by saying DNA is non overlapping
each base is only part of one triplet/codon, each triplet/codon codes for just one amino acid
describe the method of extracting DNA from fruit
+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
what is a gene
a section of DNA that codes for a sequence of amino acids in a polypeptide chain
3 types of RNA
tRNA-transport RNA
mRNA-message RNA
rRNA- ribosomal RNA
where does transcription take place
where does translation take place
transcription-nucleus
translation-cytoplasm
Outline protein synthesis stage 1
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
outline protein synthesis stage 2
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.
what is a polysome
groups of ribosomes joined by a thread of mRNA that can produce large quantities of a particular protein
define mutation
a permanent change in the DNA of an organism
what are gametes
haploid sex cells produced by meiosis that fuse to form a new diploid cell (zygote) in sexual reproduction
what is a point mutation
It is a gene mutation , is a change in one or a small number of nucleotides affecting a single gene.
identify and define 3 types of point/gene mutations
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
what are chromosomal mutations
changes in the positions of entire genes within a chromosome
what is a whole chromosome mutation
the loss or duplication of a whole chromosome
what is sickle cell disease
sickle cell anaemia- human genetic disease affecting the protein chains making up the haemoglobin in red blood cells.
what is a mutagen
anything that increases the rate of mutation
identify some types of chromosomal mutations
inversions
gene deletion
gene duplication
describe structure of collagen
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.
describe the structure of Haemoglobin
Globular protein
4 polypeptide chains joined by disulphide bonds in a quaternary structure
difference between antisense and anticodon
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.
