cellualr control Flashcards
RNA polymerase and DNA polymerase are both enzymes. RNA polymerase is involved in the action of some control elements, whereas DNA polymerase is not.
Describe and explain the difference between the functions of these two enzymes. (4)
- rna polymerase makes m,r,t RNA
- transcription
- dna polymerase
- dna replicatiom
- semi conservative
Programmed cell death is known as ……………………………………….. . Firstly, the fine network of protein filaments and microtubules known as the ……………………………………. , which gives structure to the cell, is broken down and digested by ……………………………………… .
The plasma (cell surface) membrane then changes, forming small bulges called ‘blebs’. The cell breaks into membrane-bound fragments that are removed by the process of …………………………………………… so that harmful substances are not released into surrounding tissues.
Programmed cell death is a controlled process. However, mutation in a gene called p53 can prevent programmed cell death. When this occurs, the rate at which somatic cells are produced by the process of ……………………………………………… becomes greater than the rate at which cells die, resulting in the formation of a mass of cells known as a
……………………………………….. .
- apoptosis
- cytoskeleton
- enzymes
- phagocytosis
- mitosis
- tumour
State what is meant by a homeobox gene. (2)
- regulatory gene
- 180 bp
- codes for a homeodomain on a protein
- swicthes genes on and off
Homeobox genes show ‘astonishing similarity across widely different species of animal’. Explain why there has been very little change by mutation in these genes. (2)
- these genes are very important
- mutations would hv big effects
- other genes would be affceted
State the stage(s) in which the following events occur:
independent assortment ……………………………………………….. formation of the spindle apparatus ……………………………………………….. separation of sister chromatids ……………………………………………….. formation of nuclear membranes ……………………………………………….. chromosomes pulled to opposite poles ………………………………………………..
- metaPhase 1 11
- prophase 1
- Anaphase 11
- Telophase 11
- ANAPHASE 1
Meiosis is used in many organisms for the production of gametes.
Explain why meiosis needs to have twice as many stages as mitosis. (2)
- to halve chromosome number
- seperate homologous pairs
Discuss the possible effects that mutation can have on the structure and function of a
protein (3)
- different primary , secondary , tertiary structure
- protein shorter due to deletion or longer due to insertion
- protein unchanged due to silent mutation
Suggest why a genome has to be fragmented before sequencing. (2)
genome too big
accuracy better
Name two modern techniques or procedures that can be used in the selective breeding of dairy cows.
(2)
cloning
artificila insemination
in vitro fertilisation
State what is meant by gene mutation.
chnage to dna
All human babies produce the enzyme lactase. The genetic change that allows adults to produce this enzyme is thought to involve a mutation in a regulatory gene. This mutation causes the structural gene to be expressed in adults.
Distinguish between the terms ‘regulatory gene’ and ‘structural gene’. (2)
- regulatory - makes repressor protein
- switches gene on and off - makes protein
- regulatory gene controls the expression of structural gene
The control of the expression of the lac operon genes, which allow uptake and digestion of lactose in the bacterium Escherichia coli, is well known.
Fig. 1.2 shows the arrangement of the elements of the lac operon.
Fig. 1.2
Describe how genes Z and Y are switched on in bacteria that are moved to a nutrient medium
that contains lactose. (3)
- lactose binds to repressor protein
- changes shape of protein
- removes it from binding to operator
- RNA polymerase binds to promoter
- so z and y are trasncribed
