Unit 1 Flashcards
What are eukaryotes?
Cells which have a membrane bound nucleus which stores genetic material.
What are the cells of eukaryotes?
Animals, plants, and fungi.
What are prokaryotes? Give examples of what they do/don’t have.
Cells which do not have membrane bound organelles.
They do not have mitochondria or the nucleus.
What cells are prokaryotes?
Bacteria.
Structures which both the eukaryotes and prokaryotes have?
Cell membrane, cytoplasm, cell wall.
What are codons?
The series of base triplets which make up RNA.
What are nucleotides consisted of?
A base, a deoxyribose sugar, and a phosphate group.
Give full names of A, T, C, and G.
Adenine, thymine, cytosine, and guanine.
What holds the nucleotides together?
Strong chemical bonds.
State the numbers on the dna strand, starting with the top left, then top right, bottom left, then bottom right.
5’, 3’, 3’, 5’.
What is meant by anti-parallel?
When two strands are side by side, but are going in opposite directions.
What is PCR? What does it stand for?
Polymerase chain reaction.
What is PCR? Give def.
PCR is the method to make multiple copies of a target DNA sequence.
What is required to carry out PCR?
Buffer, template DNA, primers, nucleotides, DNA polymerase.
What’s the use of PCR? What can/does it do?
Can be used to diagnose early malignant diseases, like leukaemia or aids.
Give the steps of PCR.
- DNA molecule is denatured, which will break hydrogen bonds.
- DNA is left to cool, primers bind themselves to target strands.
- DNA is then reheated, so primers can extend.
What is gene expression? Give def.
Gene expression is when specific genes are activated to produce a required protein.
What processes make up gene expression?
Transcription and translation of DNA sequences.
What is transcription?
The first step in protein synthesis.
Where does transcription start and end?
Starts at the promoter, ends at the terminator.
What are introns?
Non-coding regions.
What are exons?
Coding regions.
What types of RNA are involved with gene expression?
mRNA, tRNA, rRNA
What enzyme is required during transcription?
RNA polymerase.
Where does transcription occur?
In the nucleus.
What is cellular differentiation? Give def.
Differentiation is the process in which unspecialised cells become specialised to perform a specific function.
What happens during differentiation? Give steps.
- Many essential genes remain switched on.
- Some genes for specific characteristics are switched on.
- Unnecessary genes are switched off.
Give examples of differentiation.
Sperm: have tails to allow them to swim.
Red blood cells: have increased surface area to be able to carry more oxygen.
What is the cost of differentiation? What does this mean?
Cells which are specialised often cannot make copies of themselves. This results the storage of stem cells so the body can replenish these cells whenever needed.
What are meristems?
Meristems are regions of unspecialised cells in plants, which are capable of cell division (growth). These unspecialised cells also have the ability to become any specialised cell.
what process is responsible for growth in plant cells?
Mitosis, elongation, division.
Where are meristems?
At the tip of the roots and shoots.
What are stem cells?
Cells which can constantly undergo cell division, and can become any cell.
What are the two types of stem cells?
- Embryonic stem cells (found in embryos)
- Adult (tissue) stem cells (found in children and adults)
What do embryonic stem cells do?
They can differentiate into all cell types and make up an organism, important for growth.
What do adult stem cells do?
To replenish differentiated cells that need to be replaced and give rise to a more limited range of cell types (multipotent).
Describe potential therapeutic uses for stem cells.
Used to repair damaged or diseased organs, helps transplants and skin grafts for burns.
Also been used to find out how disease happens, and how to treat it.
What’s a genome?
A genome of an organism is its’ hereditary information encoded in its’ DNA.
What is the genome made of?
The genome is made out of genes that code for proteins, and other non-coding DNA sequences.
Most of the genome is consisted of non-coding regions. How true is this?
It is true for eukaryotic cells.
Functions of non-coding regions?
- Regulating transcription
- Transcription of RNA
- No known function.
What are mutations? What happens?
Mutations are changes is the DNA. This results in either no proteins being made, or a different protein being made.
What are single gene/point mutations?
The alternation of a DNA sequence.
What are chromosome structure mutations?
When mutations affect the structure of one or two chromosomes.
What are the 3 types of single gene/point mutation?
- Substitution.
- Insertion.
- Deletion.
What happens during substitution?
when a nucleotide is replaced by another.
What happens during insertion?
when one or more nucleotides are inserted into a DNA sequence.
What happens in deletion?
When one or more nucleotides are deleted from a DNA sequence.
What is the result of substitution?
Affects one codon. Affects them by either; missense, nonsense, or splice-mutations.
What is the result of insertion and deletion?
Frame-shift mutations.
What happens during missense in substition?
Changes the codon, causes a different amino acid to be produced. Results in the amino acid shape changing, but may not have any major effects.
What happens during nonsense in substitution?
Causes stop codon to be produced, results in shorter protein being made. Short protein means it cannot function, or its function is affected.
What happens during splice-site in substitution?
Affects splice-sites (boundaries between exons and introns), can prevents splicing at the site. Results in very different protein to be made.
What is frame-shift mutation? Which single gene/point mutation does this apply to?
Occurs in deletion and insertion. This result in the codon being shifted by one codon, which causes it to be read differently. This results in a completely different protein being made and is usually non-functional.
What is vertical gene transfer? Give def.
When genes are transferred from parent to offspring.
What is horizontal gene transfer? Give def.
When genes are transferred between each other in the same generation.
In what cells does vertical gene transfer occur?
Eukaryotic cells.
In what cells does horizontal gene transfer occur?
Prokaryotic cells.
What are the 4 types of chromosome structure mutations?
- deletion
- translocation
- inversion
- duplication
What happens during deletion in chromosome structure mutation?
Where a section of a chromosome is removed.
What happens during translocation in chromosome structure mutation?
Where a section of a chromosome is added to another chromosome, that is not its homologous partner.
What happens during inversion in chromosome structure mutation?
Where a section of chromosome is reversed.
What happens during duplication in chromosome structure mutation?
When a section of chromosome is added from its homologous partner.
When chromosome mutations happen, are they deadly?
Yes, they are often lethal as they change the chromosome structure.
What are the types of selection?
- stabilising
- directional
- disruptive
What happens in stabilising selection? What does this result in?
When an intermediate (average) phenotype is favoured whilst an extreme phenotype is against.
This results in a reduction in genetic diversity.
What happens in directional selection? What does this result in?
When one extreme phenotype is favoured.
Results in a progressive shift in population’s mean.
What happens in disruptive selection? What does this result in?
When two or more extreme phenotypes are favoured for, at the expense of average phenotypes.
Results splitting group into two distinct groups.
What is natural selection?
A random increase in the frequency of DNA sequences, which increase survival chances and are not random. Also known as survival of the fittest.
What’s a species? Give def.
A species is a group of organisms which can interbreed to create fertile offspring.
What are the 3 main stages which lead to the formation of a new species?
- Isolation by barrier (geographical)
- Mutation
- Natural selection
What is genomic sequencing?
Genomic sequencing is the process of figuring out DNA nucleotides or bases for an entire genome.
What is genomics?
The study of genomes.
What is bioinformatics?
The use of computer programs which can identify base sequences and (analyse them) look for other sequences familiar to genes.
When is genomic sequencing used?
- comparison of genomes from different species in research
- personal genomics and/or health
- Phylogenetics
Sequencing can improve research, such as?
- sequence of disease: causing organism can rule out accurate disease.
- sequence of pest species can help identify risks and find a different method of control rather than pesticides.
- sequences of model species can be used for medical research rather than using mammals.
What is phylogenetics? Give def.
Phylogenetics is the process in which genetic sequencing can be used to work out the evolutionary relationships of different species/groups of organisms.
which gene transfer allows a faster evolution?
Horizontal.
what do molecular clocks measure?
it measures the mutations in a dna sequence over time.
Or; it measures the changes in a genome over time.
What is comparative genomics?
Comparative genomics is the comparison of genomic features in different/same organisms.
What is allopatric speciation caused by?
a geographical barrier.
What is sympatric speciation caused by?
Ecological or behavioural barrier.
what can phylogenetics be used to work out?
lineage and sequence divergence
what is lineage?
the exact sequence which can be traced back through ancestor populations.
what is sequence divergence?
how and when lineages diverged from common ancestry.
What does mutant mean?
When the change in genotype affects the phenotype.
Process in which many proteins can be made from a single gene?
- Alternative splicing
- Post translational modification
Difference between RNA splicing and Alternative splicing?
RNA splicing - when only exons are in the final mature transcript.
Alternative splicing - when exons and introns are included in the final mature transcript.
