Stuff Need To Know For The Exam

Question 1

Regulation of gene expression at transcriptional level

Answer 1

• lac operon
• trancription factors - short non coding pieces of rna that act within a cells nucleus, activate or supress transcription of the gene - tumour supressor genes and proto-oncogenes

Question 2

Post transcriptional gene regulation

Answer 2

• introns and exons - introns are non coding parts of DNA some may encode proteins and some may be short non coding lengths of RNA involved in gene regulation

Question 3

Post translational level of gene expression

Answer 3

• enzymes are activated by being phosphorylated

Question 4

Describe how post translational activation happens

Answer 4

• hormone binds to receptor on plasma membrane of target cell
• actives g protien
• actives adneyl cyclase
• converts ATP to cAMP
• cAMP activates PKA
• PKA catalyses phosphorylation of proteins hydrolysing ATP in the process, activates enzymes in the cytoplams
• PKA phosphorylates CREB
• enters nucleus and acts as a transcriptional facotr

Question 5

Homeobox sequence

Answer 5

180 base pair found within gene that are involved in regulating patterns of anatomical development in animal fungi and plants

Question 6

What is the homeodomain sequence

Answer 6

Homeodomain sequence can fold into a particular shape and bind to DNA regularing transcription of adjacent genes
60 amino acid sequence
Contains two alpha helixes connected by one turn
Binds to TAAT sequence of the enhancer region

Question 7

How are hox genes regulated

Answer 7

• gap genes and pair rule genes - regulatated by maternally supplied mRNA from egg cytoplasm

Question 8

Apoptosis

Answer 8

Chromatin condenses, nuclear envelope breaks down

DNA breaks into fragments

Question 9

Physical mutagenic agents

Answer 9

X rays
Gamma rays
Uv light

Question 10

Chemical agents

Answer 10

Mustard gas
Nitrous acid
Aromatic amines
Reactive oxygen

Question 11

Biological agents

Answer 11

Viruses
Transposons - jumping genes and remnants of viral nucleic acid that have become incorporated into genomes
Food contaminants such as mycotoxins from fungi

Question 12

Deletion

Answer 12

Part of chromosome is lost

Question 13

Inversion

Answer 13

A section of chromosome mag break off turn 180 degrees and join again

Question 14

Translocation

Answer 14

• piece of one chromosome breaks off and attaches to another chromosome

Question 15

Duplication

Answer 15

When chromosome is duplicated

Question 16

Non disjunction

Answer 16

One pair of chromosomes or chromatids fails to separate leaving one gamete with an extra chromosome

Question 17

Aneuploidy

Answer 17

Chromosome number is not an exact multiple of the haploid number for that organism

Question 18

Polyploidy

Answer 18

If a diploid gamete is fertilised by a haploid gamete the resulting zygote is triploid

Question 19

Codominance

Answer 19

Where both alleles present in the genotype of a heterozygous individual contribute to the indiviudals phenotype

Question 20

Multiple alleles

Answer 20

Characteristics for which there are three or more alleles in the populstioms gene pool

Question 21

Epistasis

Answer 21

Interaction of non linked gene loci where one masks expression of the other

Question 22

Geographical isolation

Answer 22

Allopatric speciation

Question 23

Reproductive isolation

Answer 23

Sympatric speciation

Question 24

Describe pyrosequencing

Answer 24

• long length of DNA is cut into fragments of 300-800 base pairs using a nebuliser
• lengths are then degraded into single stranded DNA these are the template DNas and are immobilised
• sequencing primer is added and DNA is incubated with enzymes DNA polymersse, ATP sulfurylase , luciferase , apyrsse and the substrates adenosine 5 phosphosulfate and luciferin
• only one of the 4 possible activated nucleotides ATP, TTP, CTP and GTP are added and any light detected is generated
• one activayed nucleotode incorporated into a complimentary strand of DNA uses the strand to be sequenced as a template as this happens two extra phosphoryls are released as pyrophosphate
• in the presence of APS the the enzyme ATP sulfurylase converts the pyrophosphate to ATP
• in the presenxe of this ATP enzyme luciferase converts luciferin to oxyluciferin
• this creates visible light which can be captured by a camera
  The amount of visible light is proportional to the amount of ATP available

Question 25

Application of gene sequencing

Answer 25

Comparisons between species
Evolutionary relationships
Variation between individuals

Question 26

PCR temperatures

Answer 26

95 break h bonds
68 anneal primers
72 taq DNA polymersee additon of nucleotides im 5 to 3 direction

Question 27

What are the vegetative parts of the plant

Answer 27

Runners stolens - grow on the surface, grow horizontal- can form roots at certain points
Rhizomes - grow underground - grow horizontally can form roots at certain points
suckers - new stems that grow from the roots- horiztonal branch might die leaving new stem as a separate individual
Bulbs - overwintering mechanims, undergound stem grows from a series of fleshy leaf bases, apical bud each grow into new plants
Corns - solid underground stem scaly leave and buds that grow into new plants
Leaves - immature plants drop of and take root
Tubers - underground stem, grow into one or more plants

Question 28

Efficiexy of biomass tranfer

Answer 28

Biomass at higher trophic level/ biomass at lower trophic level x 100

Question 29

What is productivity

Answer 29

The rate of production of new biomass by producers

Question 30

Work out net primary productivity

Answer 30

Gross primary productivity- respiration

Question 31

Succession on a rock

Answer 31

Algae and lichems pioneer community
Erosion of rock and build up of dead rotting organic material produce enough soil for larger plants like mosses and ferns to grow succeding the lichens and algae
Reach climax community

Question 32

Sand dunes

Answer 32

Sea rocket sea sandwort - tolerate salty water
Sea sandwort and sea couch grass - underground stems help stabilise the sands
Sea spurge and marram grass - traps wind blown sand shoots grow taller trapping more sand
Leguminous such as hares foot clover and birds foot recoil which convert nitrogen into nitrate