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Higher Biology Unit 1
Terms in this set (155)
What is genomics?
The study of genomes.
What is a mutation?
A change in an organisms DNA
What is meant by "genome".
All of an organisms hereditary information encoded within its DNA.
What is cellular differentiation?
The process by which an unspecialised cell becomes a specialised cell.
What is meant by genotype?
The sequence of DNA bases
Which process occurs in the cells before mitosis to ensure each daughter cell gets identical copies of the genetic material?
DNA is composed of repeating units called
What is evolution?
The process of gradual change in the characteristics of a population that occurs over many generations.
What is meant by phenotype?
The physical and chemical state of the cell determined by the proteins that are synthesised.
A DNA nucleotide is made of
Deoxyribose sugar, phosphate, base
Where on the DNA strand does DNA replication take place?
What is vertical inheritance?
DNA is passed from parents down to offspring.
How does differentiation occur?
Some genes are switched off and others on.
What is the function of the coding regions of the genome?
Transcribed and translated to make proteins.
What are gene/point mutations?
A change in one (or a few) bases in an organisms DNA sequence in one gene.
What is a restriction endonuclease?
An enzyme which cuts DNA at a specific sequence.
What is gene expression?
A gene being transcribed and translated to make a protein.
The DNA bases are
Adenine, Guanine, Thymine, Cytosine
Which enzyme is needed for DNA replication?
What is bioinformatics?
The use of computers and statistics to analyse DNA sequences.
What is meant by a specialised cell?
A cell with a specific structure and function.
What are the functions of the non-coding regions of the genome?
Transcribed but not translated to make tRNA, rRNA and RNA fragments
Protect the ends of chromosomes from fraying
What are the three gene mutations?
Substitution, Insertion, Deletion
What is horizontal inheritance?
DNA passed from one cell to another,
Which types of organisms have had their genomes sequenced?
Model organisms, Pest species, Viruses and bacteria
Which organisms use vertical gene transfer?
What happens in substitution?
One base is swapped with another base.
What makes a cell become specialised?
Expressing genes which make proteins specific to the cells.
What chemical elements are proteins made of?
Carbon, hydrogen, oxygen, nitrogen.
What is a primer?
A small chain of DNA which provides a starting point for DNA polymerase.
The shape of a DNA molecule
What subunits are proteins made of?
Which direction does DNA polymerase work in?
5' -> 3' direction.
The 5' end of DNA has what at the end?
What is a stem cell?
An unspecialised cell with the potential to self-renew by mitosis or differentiate into specialised cells.
How can you tell how closely related species are from the genomes?
The more similarities there are in the DNA sequences the more closely related the species are.
What happens in deletion?
One base is removed from the DNA sequence.
Which organisms can use horizontal gene transfer?
Prokaryotes -> Prokaryotes
Prokaryotes -> Eukaryotes
Viruses -> Prokaryotes
Viruses -> Eukaryotes
What is a polypeptide?
A chain of amino acids joined by peptide bonds.
What is phylogenetics?
The study of evolutionary relatedness.
What is the role of DNA polymerase?
To add free DNA nucleotides to the 3' end of a growing DNA strand.
The 3' end of DNA has what at the end?
What is a meristem?
A region of unspecialised cells in a plant capable of cell division.
What happens in insertion?
One base is added to the DNA sequence.
What are the benefits of horizontal gene transfer?
Can lead to rapid evolutionary change.
How can we produce phylogentic trees?
Using fossil records and sequence data .
Which mutations have a frameshift effect?
Insertion and deletion.
What is an embryonic stem cell?
A stem cell with the potential to become any of the cells required in your body.
Which type of bond joins two amino acids together?
Which enzyme joins fragments of DNA together?
These bonds hold adjacent nucleotides together
Covalent bonds / Strong Chemical bonds
What is a downside of horizontal gene transfer?
There is some risk as not all genes are helpful, some may be harmful.
What type of bonds occur between amino acids that lead to folding of polypeptides?
Hydrogen bonds and sulphur bridges
These bonds hold the strands of DNA together and are found between complementary bases
Which strand of DNA is synthesised continuously?
What is meant by a frameshift mutation?
A mutation which alters every amino acid after the mutation leading to a faulty protein being produced.
What word can be used to describe the potential of embryonic stem cells to become any of the body cells?
What is a molecular clock?
A way of working out how long ago species diverged by looking at the number of mutations that have taken place. The rate of mutations is relatively stable.
What is natural selection?
The non-random increase in frequency of genetic sequences which increase an organisms chances of survival.
What gives a protein its function?
The shape of the protein gives the protein its function.
Which strand of DNA is synthesised discontinuously?
Which DNA base pairs with Adenine?
What is an Tissue (adult) stem cell?
A stem cell with the potential to become a narrow range of cells required in the body.
What is meant by a missense mutation?
Leads to a different amino acid being used so a different protein is produced.
What is sexual selection?
The non-random increase in frequency of genetic sequences which increase an organisms chances of successfully reproducing.
What are the three domains of life?
Bacteria, Archaea, Eukaryotes.
What is the sequence of evolution of life on earth?
Prokaryotes -> Photosynthesis -> Eukaryotes -> Multicellular organisms -> Animals -> Vertebrates -> Land plants
Describe the process of natural selection?
Organisms which are better suited to their environment are more likely to survive and reproduce and are more likely to pass on their genes to the next generation.
What is meant by a nonsense mutation?
Premature stop codon inserted. Different / no protein produced.
What word can be used to describe the narrow differentiation potential of tissue (adult) stem cells?
What gives a protein its shape?
The order of the amino acids and the folding of the polypeptide chain.
What is meant by discontinuous replication?
Strand is synthesised in fragments
Which DNA base pairs with Guanine?
What is a eukaryote?
Organism with membrane bound organelles and a true membrane bound nucleus.
What is needed in the cell to allow DNA replication?
Template DNA, primers, DNA polymerase and ligase (enzymes), free DNA nucleotides, ATP
What determines the order of amino acids in a polypeptide chain?
The order of DNA bases in the gene which codes for the protein.
What is function of Tissue (adult) stem cells?
They provide a supply of differentiated cells needed for growth and repair in organisms.
What is meant by a neutral mutation?
A mutation which leads to the same amino acid being produced so no change in protein produced.
What are the three ways that natural selection can affect the frequency of particular traits?
What is the use of personal genomics?
Knowing the risk of developing diseases
What is pharmacogenetics?
Being able to prescribe medication that is personalised to a persons genome to make sure it is the correct drug and dosage.
What is meant by directional selection?
The mean trait shifts towards one of the traits that was less common previously.
What is meant by a silent mutation?
A different but chemically similar amino acid is used to protein still functions correctly.
How can stem cells be used therapeutically?
- In bone marrow transplants to treat leukaemia
- To treat damaged cornias
- To grow skin grafts to treat burns
Which process produces a primary mRNA transcript?
What is a prokaryote?
Organism which does not have a nucleus and does not have membrane bound organelles.
Where is DNA found in eukaryotes and what form are they in?
Linear chromosomes in the nucleus
Circular chromosomes in the mitochondria and chloroplast
Which enzyme is required to make a molecule of mRNA?
What is meant by the frequency of mutation?
How often the mutation occurs.
What is meant by stabilising selection?
The mean trait is maintained and more organisms sow the mean trait reducing genetic diversity.
What are the ethical issues associated with personal genomics?
- Potential bias from employers
- Potential bias from life insurance
- Potential distress from knowing about risks of disorders.
What is meant by disruptive selection?
The extreme versions of the trait are favoured resulting in two new mean traits. The intermediate traits become less common.
How often do mutations occur?
Randomly and rarely.
What are the differences between RNA and DNA
RNA - single stranded DNA - double stranded
RNA - uracil DNA - Thymine
Which organisms are eukaryotes?
Animals, plants, fungi (yeast)
How can stem cells be used in research?
- To study cellular processes
- To use as model cells in drug testing
- To investigate causes of disease
Which organisms are prokaryotes?
What is a mutagen / mutagenic agent?
Something which increases the frequency of mutations.
Which process allows us to amplify DNA in vitro?
Polymerase Chain Reaction (PCR)
Give an example of a mutagenic agent?
Mustard gas, U.V. radiation, X-Rays
Where is DNA found in prokaryotes and in what form?
Large circular chromosome, plasmids
What is the first stage in transcription?
RNA polymerase unwinds and unzips DNA strand.
What are the stages of PCR?
1. Heating up to 94C-96C
2. Cooling to 50C -65C
3. Heating up to 72C
What is a plasmid?
Small ring of DNA
How can mutations alter gene expression?
If a mutation occurs DNA sequence that regulates transcription then this can lead to transcription being halted.
What are the ethical implications of using stem cells in medicine or research?
- Using embryonic stem cells leads to embryos being destroyed which some people believe is murder
- Embryonic stem cells come from embryos which would have been destroyed any way so people believe they should be used for good
How can you tell if two organisms are the same species?
If they can interbreed to form fertile offspring then they are the same species.
Which mutation can lead to introns being left in the mature mRNA transcript?
Splice site mutations.
What is the role of RNA polymerase in transcription?
Unwinds and unzips the DNA double helix. Adds RNA nucleotides to form a molecule of mRNA.
Which eukaryotes contain plasmids?
What is mRNA?
What is speciation?
The formation of new species.
How are mutations beneficial for evolution?
They provide new variation upon which natural selection can act.
How is DNA packaged in linear chromosomes?
Tightly wound around proteins called histones
What are some of the future therapeutic uses of stem cells?
Treatment of parkinson's or alzheimer's disease.
Why is DNA said to be antiparallel?
One strand runs in the 3'->5' direction, the other runs in the 5' -> 3' direction.
What is required for PCR?
Primers, DNA (Taq) Polymerase, Free DNA nucleotides, Template DNA, buffer
What is the function of mRNA?
To carry a complimentary copy of the DNA sequence from the chromosomes in the nucleus to the ribosome in the cytoplasm.
What is a chromosome mutation?
A change in the number or sequence of genes on a chromosome.
Summarise the events in speciation.
1. Isolating barrier
3. Natural Selection
4. Many generations
5. Two new species are formed
Why is buffer required in PCR?
To keep a stable pH
What is a ribosome made of?
rRNA and protein
What is an induced pluripotent stem cell?
A stem cell produced by taking differentiated cells and reprogramming them to revert back to becoming stem cells.
What are the chromosome mutations called?
Translocation, Inversion, Deletion, Duplication
What are the three types of isolating barriers?
Geographical, ecological, behavioural.
What is the function of the ribosome?
The site of protein synthesis.
What is an application of PCR?
Paternity testing, crime scene analysis and working out evolutionary relationships
What happens during translocation?
Genes from one chromosome become attached to the end of another chromosome.
What is sympatric speciation?
Speciation which occurs as a result of a behavioural barrier.
Which process allows the formation of a mature mRNA transcript?
What is allopatric speciation?
Speciation which occurs as a result of a geographical or ecological barrier.
What happens in inversion?
The order of genes gets swapped around (ABC becomes CBA).
What happens in duplication?
Some of the genes become copied and inserted into the chromosome.
What is an exon?
A coding section of mRNA
Why is DNA heated to 94C-96C in PCR?
To separate the two DNA strands by breaking the hydrogen bonds between complimentary bases.
What happens in deletion?
Some of the genes are removed from the chromosome.
What is an intron?
A non-coding section of mRNA
How can duplication result in new characteristics?
The original information is still present so the genes can function. If mutations occur in the extra copies of the gene they can lead to new characteristics.
What happens during splicing?
The introns are removed and the exons are joined together to make the mature mRNA transcript.
Where does transcription begin?
At a start codon
Why is DNA cooled to 50C -65C during PCR?
To allow the primers to anneal to their target sequences.
Why is DNA heated to 72C during PCR?
To allow DNA polymerase / Taq Polymerase to build new strands by adding free DNA nucleotides.
What is a codon?
Three bases on mRNA which codes for one amino acid
Why are two primers needed in PCR?
One primer for each strand
What is meant by a positive control in PCR?
A control with a known sequence of DNA to show that all of the components are working.
What is tRNA?
What is the function of tRNA?
Have an anti-codon which is complementary to a codon on mRNA. Carries specific amino acids to the ribosome.
What is meant by a negative control in PCR?
A control which lacks a DNA sequence to show that there is no contamination.
What is an anticodon?
Three bases on a tRNA molecule which matches with a codon on mRNA.
What is the process which synthesises a protein using the information carried in mRNA?
Where does translation end?
Which process can allow many different proteins to be produced from one gene?
How many codons code for one amino acid?
How many bases are in a codon?
How many bases code for one amino acid?
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