topic 8- mutations and gene expression

Question 1

what is a mutation

Answer 1

a change in the DNA base sequence

Question 2

what is a substitution mutation

Answer 2

are when a base on the code is copied incorrectly and is substituted for another.

Question 3

what is a deletion mutation

Answer 3

when a base is removed from the sequence causing a frame shift in the sequence to the left

Question 4

what is an addition/insertion mutation

Answer 4

extra base is inserted in the sequence that has a similar effect to a base deletion that causes a frame shift to the right

Question 5

what is a duplication mutation

Answer 5

One or more base is repeated, and it produces a frame shift to the right

Question 6

what is an inversion mutation

Answer 6

a group of bases become separated from the DNA rotate and go back in causing it to be reversed and therefore effecting the amino acid that is sequenced for

Question 7

what is a translocation mutation

Answer 7

a group of bases is moved from one location to another within the chromosome to a different chromosome

Question 8

what is a mutagenic agent and an example

Answer 8

Mutagens are outside factors that can increase the mutation rate
e.g. gamma rays, alpha and beta particles

Question 9

how do mutagenic agent increase the mutation rate

Answer 9

1. They can act as a base which can be substituted for a base during DNA replication
2. alter base sequence by deleting alternate bases
3. changing the DNA structure like UV radiation causing adjacent bases that we dont want

Question 10

what is an hereditary mutation

Answer 10

If a gamete containing a mutation is fertilised it will be present in the new foetus

Question 11

what is a benefit of mutations

Answer 11

increases genetic diversity necessary for survival

Question 12

what are stem cells

Answer 12

unspecialised cells that can make a new copy of itself or become specialised

Question 13

what genes are permanently expressed

Answer 13

enzymes involved in respiration , transcription and translation

Question 14

what is cell speciation

Answer 14

The process by which a cell develops into a specialised cell suited to its role by genes being expressed and it is irreversible

Question 15

what does totipotency mean and where are they found

Answer 15

has the ability to give rise to all types of cells

normally fertilised egg

Question 16

what is pluripotency and where are they found

Answer 16

Can still specialise to become anybody cells but lose the ability to make up the placenta

found in a mature embryo from the IVF process

Question 17

what is multipotency and where are they found

Answer 17

Found in adults and can differentiate into a limited number of specialised cells

Bone marrow can become any type of blood cell

Question 18

what is unipotency and where is it found

Answer 18

Can only differentiate into a single type of cell

Made in adult tissue

Question 19

what are induced pluripotent cells and why are they made

Answer 19

made to express a series of transcriptional factors normally associated with pluripotent stem cells and these cause the adult body cell to express the genes and divide indefinately and become a stem cell

Question 20

what are the uses of pluripotent stem cells

Answer 20

can be used to regrow tissues that have been damaged like burns and ones affected by parkinsons

Question 21

what is a transcription factor

Answer 21

something that controls the transcription of genes

Question 22

where are transcription factors found

Answer 22

they are proteins in the cytoplasm

Question 23

how do transcription factors work

Answer 23

they move into the nucleus and attach themselces to the DNA by the promotor region of a specific base sequence near their target zone

Question 24

what are activator

Answer 24

increase the rate of transcription as they help RNA polymerase bind to the promoter region

Question 25

what are repressors

Answer 25

inhibit or slow the rate of transcription and they bind to the promoter region and prevent RNA polymerase from binding

Question 26

outline how Oestrogen has an effect on gene transcription

Answer 26

1. oestrogen is lipid soluble and can diffuse through phospholipid membrane and diffuse into the ctyloplasm
2. oestrogen binds to an oestrogen receptor on a transcription factor forming a complex and changing the shape of the transcription factor
3. transcription factor diffuses through the nuclear pore and gets to the DNA in the nucleus where it binds to a promotor region on a specific base sequence and this stimulates transcription of the gene

Question 27

what is epigenetics and how is it influenced

Answer 27

inheritable changes in gene function without changes to the base sequence of DNA

-the environment can influence gene expression without changing the base sequence e.g. diet, stress

Question 28

what is the epigenome

Answer 28

Epigenome is all the chemical modifications to all histone proteins and DNA in an organism

Question 29

how do epigenetic markers work

Answer 29

1. attach or remove chemical groups and this alters how easilt transcription enzymes and other proteins interact with the DNA

Question 30

what happens to epigenetic markers between generations

Answer 30

Most epigenetic markers are removed between generations after fertilisation however some are passed on to the offspring

Question 31

what is epigenetic silencing

Answer 31

when the histone DNA complex is too condensed to be transcribed

Question 32

what happens when the association of histones with DNA is strong

Answer 32

the complex is more condensed and accessible by transcription factors which cannot initiate production of mRNA so the gene is switched off.

Question 33

what happens when the association of histones with DNA is weak

Answer 33

the complex is less condensed so this means the DNA is accessible by transcription factors to make mRNA so the gene can be expressed/ switched on

Question 34

outline how methylation increases