DNA and RNA Past Mock Questions Flashcards
Distinguish between DNA profiling and genetic screening
DNA profile
DNA profiling is a method of making a unique pattern of bands from the DNA of a person, which can then be used to compare with the DNA profile of another person
Distinguish between DNA profiling and genetic screening
Genetic screening
Genetic screening means testing DNA for the presence of absence of a particular gene or an altered gene
During your investigation to isolate DNA from a plant cell, describe how you broke down the cell wall
The union was also chopped into small cubes and blended for three seconds to break down the cell walls and release DNA
During your investigation to isolate DNA from a plant cell, describe how you broke down the cell membrane
Washing up liquid was used as it dissolved the cell and nuclear membranes to release the DNA
During your investigation to isolate DNA from a plant cell, describe how you precipitate the DNA
Freezer-cold/ice cold ethanol was added
What does need to be done to a plant cell but not a blood cell when trying to extract DNA?
The sample doesn’t need to be blended as there is no cell wall
On what basis are DNA fragments separated by during gel electrophoresis
They are separated based on size
Why are DNA fragments stained after electrophoresis?
To make them more visible and easier to see
To which group of bases does Guanine belong to?
Purines
Name the type of bonding that exists between strands of the DNA double helix
Hydrogen bonds
What causes the double helix of DNA to unwind?
Enzymes
Explain the function of the enzyme RNA polymerase
Causes a sequence of RNA bases to join together to form messenger RNA i.e. it joins nucleotides together to form mRNA
In which part of the cell does transcription occur?
Nucleus
In which part of the cell does translation occur?
Cytoplasm
Why is it necessary for a protein to fold?
A protein only becomes functional once its folded into its correct shape
What group of biomolecules provide the nitrogen needed to make the nitrogenous bases contained in DNA?
Protein
Name one of the purine bases found in DNA
Adenine or guanine
In the DNA molecule what base does adenine bond to?
Thymine
In the DNA molecule what base does guanine bond to?
Cytosine
Explain the importance of complementary base bonding in DNA
The bonding between complementary base pairs hold two strands of DNA in a double helix shape
In RNA what does R stand for?
Ribose
Name the type of RNA molecule made during the process of transcription?
Messenger RNA (mRNA)
In which structure of the cell does transcription occur?
Nucleus
Describe the relationship between messenger RNA (mRNA) and the DNA molecule
(2)
The mRNA molecule has complementary bases to those on the DNA strand from which it was transcribed
Thymine is replaced with uracil on the mRNA molecule
What is the final step in protein formation which gives it it’s function?
The protein must be folded into it’s correct shape
Explain the importance of heredity to living organisms
Heredity is the passing on of features from parents to offspring by means of genes
Heredity is also called genetic inheritance
Explain the phrase gene expression
Gene expression is the way in which the genetic information in a gene is decoded in the cell and used to make a protein
Explain why it is important that the correct sequence of bases is maintained during DNA replication
If the correct sequence of bases is not maintained then the production of an incorrect amino acid will result
Apart from the nucleus, name one other organelle where DNA may be found
Chloroplast
Mitochondrion
Explain what is meant by junk DNA
Junk DNA or non-coding DNA is DNA that does not cause the production of a protein
To which base does uracil bond?
Adenine
Explain the difference between the terms genetic screening and genetic engineering
(Genetic screening)
This means testing DNA for the presence or absence of a particular gene or an altered gene
Explain the difference between the terms genetic screening and genetic engineering
(genetic engineering)
Genetic engineering is the artificial manipulation or alteration of genes
Explain why it is necessary to break down the cell walls during DNA profiling
The cells are broken down to release their DNA
During DNA profiling, how is the DNA cut into sections?
Using restriction enzymes
Give an example of heredity
Humans inherit features such as number of fingers, the production of nails and the ability to form tears
Plants inherit features such as the number of petals, the colour of petals and the shape of leaves
Name the five carbon sugar found in DNA
Deoxyribose
Indicate any one way that RNA and DNA differ
1/3 differences
DNA
- contains the sugar deoxyribose
- bases are AT GC (thymine)
- double stranded (double helix)
RNA
- contains ribose
- bases are AU GC (Uracil)
- single-stranded
Give one reason why a genetic screening may be carried out
To test for the present or absence of a specific gene i.e. the gene for albinism or cystic fibrosis
To test for the presence of abnormal or altered genes
What does the m stand for in mRNA?
Messenger
During protein synthesis, transcription occurs.
What organelle does the mRNA travel to when it leaves the nucleus?
Ribosome
How many bases code for an amino acid?
3
Name one other type of RNA other than mRNA that is involved in protein synthesis
tRNA - transfer RNA
Where in the cell is tRNA located
Cytoplasm
Name one other type of RNA other than mRNA or tRNA
rRNA - ribosomal RNA
Where in the cell is rRNA located?
Ribosome
Name the everyday substance which is used in the isolation of DNA to break down cell membranes
Washing-up liquid
How does mRNA pass out of the nucleus?
Through nuclear pores
How does mRNA attach itself to a ribosome?
The mRNA strand forms weak bonds with rRNA
What does the letter t stand for in tRNA?
Transfer
How does the tRNA know at exactly what position on the mRNA to deposit the amino acid it is carrying?
It binds with the complementary bases on mRNA
Name the organelle where protein synthesis takes place
Ribosomes
Explain the term triplet
Also called a codon
A sequence of three bases in DNA or RNA that act as a code for an amino acid
State the role of triplets in protein synthesis
Each codon/triplet codes for an amino acid
Describe the role played by mRNA in protein synthesis
6
mRNA is a complementary strand to the DNA
mRNA contains a start codon and a stop codon as well as many other codons specifying amino acids
The mRNA moves from the nucleus to the cytoplasm
The mRNA strand carries instructions for the production of a protein from DNA
The mRNA bond forms a weak bond with rRNA
tRNA will then bind with mRNA until the stop codon is reached
Describe the role played by tRNA in protein synthesis
2
tRNA has a complementary anticodon to mRNA codon
tRNA carries an amino acid to the ribosome
Name one component of a nucleotide other than a base pair
Sugar - deoxyribose
Phosphate
Give a brief account of the stages involved in DNA profiling
DNA is released from cells
DNA is cut into fragments of different lengths using restriction enzymes
DNA fragments are separated according to size by electrophoresis
The patterns produced by the fragments are compared or analysed
What is a gene?
A section of DNA that causes the production of a protein
Name the two purine bases
Guanine
Adenine
Give an application of DNA profiling
Forensic science - identifying a suspect
Medicine- identifying the paternity or maternity of a person