6.1.1 cellular control

Question 1

acetylation/phosphorylation

Answer 1

the addition of acetyl/phosphate groups, to make them more negative so that the DNA can coil less tightly, and transcription can take place

Question 2

methylation

Answer 2

the addition of methyl groups to make the histones more hydrophobic so that they can bind more tightly to eachother, preventing transcription

Question 3

epigenetics

Answer 3

used to describe the control of gene expression by the modification of DNA

Question 4

operon

Answer 4

group of genes that are under the same regulatory mechanism and are expressed at the same time

Question 5

are operons prokaryotic or eukaryotic

Answer 5

prokaryotic

Question 6

lac operon

Answer 6

group of 3 genes, lacZ, lacY and lacA, involved in the metabolism of lactose - structural genes

Question 7

enzymes that the lac operon codes for

Answer 7

B galactosidase, lactose permease and transacetylase

Question 8

regulatory gene of the lac operon

Answer 8

lacI, codes for the repressor protein which prevents the transcription of the structural genes in the absence of lactose

Question 9

lac operon when lactose is absent

Answer 9

regulatory gene codes for the repressor protein
attaches to operator site
blocks the promoter site
this means RNA pol cannot attach
structural genes are not transcribed

Question 10

when lactose is present

Answer 10

a little bit of lactose enters the cell by diffusion
attaches to the repressor protein
this changes the shape of the protein, so cannot attach to operator
RNA pol can attach to promoter
structural genes are transcribed
so enzymes are made

Question 11

post transcriptional control

Answer 11

splicing

Question 12

splicing process

Answer 12

pre- mRNA (introns and exons) is then changes when introns are removed and exons are joined, forming mature mRNA
a cap is added on 5’ end and a tail is added on 3’ end for stabilising

Question 13

spliceosomes

Answer 13

the enzymes involved in splicing, can join the exons in a variety of ways, producing several versions of functional mRNA

Question 14

factors that regulate when translation starts and stops

Answer 14

• how long the mRNA lasts in the cytoplasm
• inhibitory factors
• initiation factors

Question 15

post translational control

Answer 15

addition of non protein groups
folding into final shape
activation of proteins by cAMP

Question 16

cAMP

Answer 16

cyclic AMP, can change the 3D shape of a protein, activating the active

Question 17

activation of PKA

Answer 17

1. PKA is an enzyme with 4 subunits
2. when cAMP isnt bound the 4 units are bound together and inactive
3. when cAMP binds, it causes a change in the enzymes 3d shape, releasing the active subunits, activating the enzymes

Question 18

morphogenesis

Answer 18

the regulation of the pattern of anatomical development

Question 19

homeobox genes

Answer 19

group of genes which all contain a homeobox

Question 20

homeobox

Answer 20

section of DNA 180 base pairs long coding for a protein which is 60 amino acids long (a homeodomain)

Question 21

homeodomain

Answer 21

60 amino acids long, and binds to DNA, and switches other genes on and off

Question 22

hox genes

Answer 22

a group of homeobox genes that are only present in animals, responsible for the correct positioning of body parts

Question 23

amount of hox genes in humans

Answer 23

39

Question 24

how body plans are represented

Answer 24

cross sections through the organism showing the fundamental arrangement of tissue layers

Question 25

somites

Answer 25

the segments in embryo that allow individual vertebrae to be developed, directed by hox genes

Question 26

radial symmetry

Answer 26

seen in diploblastic animals like jellyfish, no left or right, just top and bottom

Question 27

bilateral symmetry

Answer 27

seen in most animals means that organisms have both a left and right side and a head and a tail

Question 28

asymmetry

Answer 28

seen in sponges which have no lines of symmetry

Question 29

apoptosis

Answer 29

programmed cell death

Question 30

how apoptosis shapes body parts

Answer 30

removes unwanted cells and tissues

Question 31

what regulates mitosis and apoptosis?

Answer 31

hox genes

Question 32

factors affecting the expression of regulatory genes

Answer 32

environment, internal and external stress and drugs etc

Question 33

mutation

Answer 33

change in the sequence of bases in DNA or RNA

Question 34

substitution mutation

Answer 34

mutation in which a single nucleotide changes the codon in which it occurs

Question 35

degenerate code

Answer 35

multiple codons encode a single amino acid

Question 36

nonsense mutation

Answer 36

a mutation that changes an amino acid codon to one of the 3 stop codons, resulting in a shorter and non functional protein

Question 37

missense mutation

Answer 37

a base pair substitution that results in a codon that codes for a different amino acid

Question 38

insertion mutation

Answer 38

a mutation in which one or more nucleotides are added to a gene

Question 39

deletion mutation

Answer 39

a mutation in which one or more pairs are removed from a gene

Question 40

frameshift

Answer 40

mutation that causes the reading frame of mRNA codons to shift (insertion or deletion)

Question 41

no effect mutation

Answer 41

there is no effect on the phenotype of an organism because the normally functioning proteins are still synthesised

Question 42

damaging effect mutation

Answer 42

phenotype of an organism is affected in a negative way because proteins are no longer synthesised, which can interfere with essential processes

Question 43

beneficial effects of mutations

Answer 43

mutations often produce proteins with new or altered functions that can be useful to organism in changing environments

Question 44

mutagens

Answer 44

physical and chemical agents that interact with DNA to cause mutations

Question 45

physical mutagens

Answer 45

radiation x rays, UV light (break one or both DNA strands)

Question 46

chemical mutagens

Answer 46

deaminating agents - chemically alter bases in DNA changing the base sequence

Question 47

biological mutagens

Answer 47

viruses, base analogs, alkylating agents

Question 48

chromosome mutation - deletion

Answer 48

due to breakage, a piece of chromsome is lost

Question 49

chromsome mutation - inversion

Answer 49

a chromosome rearragement in which a segment of chromosome is reversed end to end

Question 50

chromosome mutation - translocation

Answer 50

a section of one chromosome breaks off and joins another non-homologous chromosome

Question 51

housekeeping genes

Answer 51

the genes that code for enzymes present in metabolic reactions that are always required

Question 52

tissue specific genes

Answer 52

the genes that code for protein based hormones which are only required a certain times to carry out short lived responses

Question 53

the different levels of gene regulation

Answer 53

transcriptional, post transcriptional, translational, post translational

Question 54

heterochromatin

Answer 54

tightly wound DNA, where RNA pol cannot access the genes

Question 55

euchromatin

Answer 55

loosely wound DNA where RNA polymerase can access the genes

Question 56

suggest reasons why fruit flies are chosen for research into genes controlling development of body plan

Answer 56

- fewer public concerns over ethics of using flies - low cost - rapid reproduction rate - fruit fly genetics is understood well

Question 57

why would mice be used in research of body plans? why not?

Answer 57

- low cost - similar to humans - however more ethical concerns