Evidence for Evolution Flashcards
1
Q
Gel electrophoresis process
A
- Fill the wells with DNA strands at the negative end.
- The electric current. DNA is negatively charged and is attracted to the positive end. After the current has been turned on, it must be left for a period of time.
- A banded pattern will occur, this is the DNA fingerprint. This pattern is created as smaller pieces are lighter and travel further than the larger pieces of DNA.
- The DNA fingerprint is used to find information regarding the DNA. Fingerprints can be compared for purposes such as paternity tests and forensic investigations, as well as comparing genomes, junk DNA and ERV’s.
2
Q
Polymerase chain reaction
A
- Denature the DNA – split it, using heat (95º).
- Annealing – attach a primer to the DNA to show where to start copying, (50-60º).
- Elongation/Extension – DNA/Taq polymerase attaches and starts building/creating the DNA. (72º).
3
Q
Why is Taq polymerase is used
A
Taq polymerase is from bacteria it is used as it is heat resistant, allowing the process to continue. Human DNA polymerase would denature, when heated and cooled.
DNA polymerase would denature as it is conditioned to work in the body at 37º.
4
Q
Steps 1-5 sanger method
A
- Obtain the DNA to be sequenced.
- Multiply the DNA through a Polymerase chain reaction.
- Repeat this process thousands of times until there is a sufficient amount of DNA.
- The thousands of pieces should be divided into 4 separate containers. Along with the DNA these containers should contain primer, DNA polymerase, deoxyribonucleotides and one type of dideoxy-nucleotides. There should be a greater percentage of normal nucleotides than dideoxy-nucleotides.
- The primer attaches to the start of the DNA strand, as it has a sequence complimentary to the strand. This triggers the polymerase to begin reading the DNA and attaching complementary nucleotides, as it does in normal DNA replication.
5
Q
Steps 6-9 of Sanger method
A
- When a dideoxy-nucleotide attaches to the strand of DNA, the replication process stops.
- Step five is repeated thousands of times. The point at which the dideoxy-nucleotides is random, this creates DNA strands of different lengths, ending in a known base.
- Gel Electrophoresis is then used to separate the different strand lengths, each of the different nucleotide solutions should be placed in a separate well.
- Reading from the positive to the negative end (shortest to longest strands), the sequence can be determined. The sequence determined is complementary to the original DNA strand.
6
Q
What is the Sanger method used for
A
This is the method used to sequence DNA.
7
Q
Recombinant DNA steps 1-3
A
- Human DNA containing the gene for desired hormone is obtained. The desired gene is cut out at the restriction site using restriction enzymes. This gives a base sequence to which the hormone would be produced.
- A bacterium containing chromosomal DNA and a ring of DNA that acted as the bacteria’s defence system known as plasmid is obtained. The plasmid is extracted
- The same restriction Enzyme is used to cut the plasmid (same enzyme used in cutting desired gene).
8
Q
Recombinant DNA steps 4-6
A
- The human gene is then combined with the plasmid to create recombined DNA. DNA ligase (enzyme) glues the DNA into place, this process is called ligation.
- The recombinant DNA is then placed back into the bacteria, using a bacteriophage. The bacteria breed in a fermenter (the perfect environment for bacteria to breed). Bacteria producing hormone breed rapidly.
- The bacteria make hormone which is collected, hormone is then purified and ready to be used.
9
Q
Junk DNA
A
- Non-coding sequences in chromosome, it has no function and appears to serve no purpose.
- The more junk sequences species have in common, the more closely they are related/more recently split from a common ancestor.
10
Q
Ubiquitous Proteins
A
- Ubiquitous proteins, are common in all organisms on earth, this implies everything evolved from a common ancestor.
- Ubiquitous protein sequences can be compared, the similar the sequences the more recently the species have evolved from a common ancestor.
11
Q
Mitochondrial DNA
A
- DNA only inherited from the mother, it has a higher rate of mutations. The mutation rate is predictable, related to the number of generations/years. Mitochondrial DNA can be compared to determine the closeness of their relationships through their maternal ancestors.
- Contains 37 genes. 13 related to cellular respiration and 24 related to protein synthesis
- The similar the mitochondrial DNA the more recently the organisms have evolved from a common ancestor.
- Mitochondrial DNA cannot be traced back millions of years, due to the rate of mutations.
12
Q
Endogenous Retroviruses
A
- Virus that enters the genome and copies its RNA into the DNA, via reverse transcription. It is always found in the same location of the genome.
- When passed into the sex cells, it can be passed down to the next generation.
- When the mutation/virus is present in a whole genome, it can be referred to as an ERV.
- The more ERV’s species have in common the more recently they have evolved from a common ancestor.
- When comparing species, if ERV appears in one species and not the other, the split from the common ancestor occurred before that ERV was inserted.
13
Q
Bioinformatics
A
- The use of computers to describe the molecular components of living things.
- It is useful to trace evolution of a large number of organisms measuring changes in their DNA rather than through traditional techniques of physical taxonomy or physiological observations.
14
Q
Genome Sequencing
A
- Genome is sequenced to compare different species, using the position of their genes. The more similar genes, suggests that the species more recently evolved from a common ancestor.
15
Q
Comparative embryology
A
- Comparison of the early development stages of organisms.
- The embryonic gill pouches and arches, in reptiles, birds and mammals, which use lungs to breath, suggests these have evolved from aquatic animals.
- The more similarities in the embryonic stages and development of embryos, the more likely these organisms have evolved from a common ancestor. They have developed differently as they are used for different functions, due to selection pressures.
