Biotechnology and Evidence for Evolution Flashcards Preview

Human Biology Unit 3 + 4 > Biotechnology and Evidence for Evolution > Flashcards

Flashcards in Biotechnology and Evidence for Evolution Deck (48)
Loading flashcards...

What is genetic engineering

Allows foreign modified DNA to be introduced into another cells


What are the implications of genetic engineering

Can replace fault genes with healthy ones

Can produce synthetic hormones such as insulin for diabetics

Can produce vaccines


Types of genetic engineering

Both types are cut by restriction enzymes

1. Straight cut and blunt ends
2. Staggered cuts and sticky ends


Step 1 of genetic engineering

Isolate gene
Cut the gene using restriction enzyme at restriction site


Step 2 of genetic engineering

Isolate a plasmid
Cut the plasmid with same restriction enzyme


Step 3 of genetic engineering

Sticky ends and plasmid DNA anneal to each other
Spliced together by ligase


Step 4 of genetic engineering

Bacteria takes up recombinant plasmid
Copies of recombinant plasmid are made
Copies placed into host cells
Host cells produce protein the gene codes for


What is electrophoresis

Profiling technique
Used to determine individuals DNA profile


Step 1 of electrophoresis

DNA fragments placed into cavities


Step 2 of electrophoresis

Electric current passed through gel


Step 3

DNA moves through to positive electrode from negative electrode


Step 4

Smaller fragments move fast
Larger fragment move slower and shorter
Forms bands of gel


Step 5

Forms a DNA fingerprint


Implications of Electrophoresis

Tracing ancestry
Forensic science
Identifying hereditary diseases


Definition of DNA sequencing

The determination of the precise order of nucleotides in a sample of DNA


What is DNA sequencing

When building a DNA strand each new nucleotide is bonded to the hydroxyl group of the previous strand,
no hydroxyl group to bond to, no additional nucleotides can be added, so chain is terminated


Step 1 of DNA sequencing

Double stranded DNA molecule is extracted


Step 2 of DNA sequencing

Denatured at 90-96 degrees
split into two
only work with the template strand


Step 3 of DNA sequencing

A primer is then annealed to the template strand


Step 4 of DNA sequencing

The copies of the unknown DNA strand are made using 4 reactions mixtures
→ Template DNA strand with primers attached
→ DNA polymerase
→ Large amount of normal deoxynucleotides (dNTPs)
→ Small amount of fluorescently dyed synthetic nucleotides called Dideoxynucleotides (ddNTPs) that don't have the hydroxyl groups present


Step 5 of DNA sequencing

DNA polymerase works in the reaction mixtures by adding nucleotides to the primer to complete the complementary strand


Step 6 of DNA sequencing

DNA polymerase continues to add free nucleotides until a synthetic dideoxynucleotide is used without the OH group which terminates the elongation of the sequence


Step 7 of DNA sequencing

We are left with a range of strands of varying lengths, all ending with one of the 4 possible fluorescently dyed dideoxynucleotides
→ This allows us to overlay the strands of various lengths to reveal the complete sequence of bases of the unknown strand


How to determine the sequence

multiple copies are added to an electrophoresis gel
a current is passed through the samples of varying lengths they move away from the negative electrode towards the positive electrode


Implications of DNA sequencing

point mutations, insertions and deletions can be detected

Diseases which can be determined such as cystic fibrosis


Definition of Polymerase Chain Reaction

Used to multiply segments of DNA through a series of repeated cycles


Step 1 of PCR


Solution is heated (94-98) degrees
The heat disrupts the hydrogen bonds causes separation of the DNA strands into single strands


Step 2 of PCR


Temperature reduced to 50-65 degrees to allow a primer, to join the complementary strand

At this temperature the primers anneal with the complementary sequence of DNA to start the replication from taq polymerase

Forward and reverse primers are needed for both sides as they are designed to bracket the DNA region to be


Step 3 of PCR


Temperature rose again to 72 degrees
Taq polymerase binds to primers
The Taq polymerase synthesises new DNA strand
Segments of single stranded DNA are replicated


Applications of PCR

DNA profiling
DNA from fossils can be amplified
Detect hereditary diseases


Gene Therapy

Aims to treat genetic abnormalities by replacing fault gene with healthy gene


Cell Replacement

Stem cells are undifferentiated cells that are capable of mitotic divisions for long periods of time. stem cells are used in genetic engineering


Gene therapy and cell replacement

Stem cells is taken from patient
Mutant gene replaced with normal gene
Cells multiply
Cells transferred back into patient


Human Genome Project

Enables us to identify mutation in a gene
Enabled us to identify the abnormal protein causing the disease
Gene therapy and genetic engineering are treatments which help genetic diseases


Ethical Considerations

Autonomy, respect the right for an individual to be tested, if tested, to know and share the information
Confidentiality, the genetic information is treated sensitively
Equity, the right to fait and equal treatment regardless of genetic information


Comparative DNA studies

In each species, the sequence of nucleotides varies. If more similar the DNA sequence then the organisms are more closely relate and are more likely to have a common ancestor.


Example of Comparative DNA studies

Endogenous Retrovirus, a viral sequence that has become apart of an organism's genome


Comparative Mitochondrial DNA studies

The higher the degree of similarity between mtDNA of two individuals the closer their evolutionary relationship


Example of Comparative Mitochondrial DNA studies



Comparative Protein Sequence Studies

Every protein has a number of amino acids. Similarity of amino acid sequence is evidence of close evolutionary relationship


Example of comparative protein sequence studies

Ubiquitous protein, Cytochrome C which performs basic tasks for cellular energy. To compare Cytochrome C sequences they need to be aligned so that the maximum number of positions containing the same amino acid can be determined. The more similarity between the molecules, the more recently they have diverged from a common ancestor


Phylogenetic Trees

Comparative studies allow scientists to work out the evolutionary relationship between groups of organisms

Phylogenetic tree represents the evolutionary relationships between organisms derived from a common ancestor

The ancestral organism forms the base of the tree and these organisms that have arised from it are placed on the ends of the branches


Comparative Embryology Studies

Comparative embryology studies will show how the closely related organisms will show similar anatomical development in the embryonic stages of life which will show they all share a common ancstor


Example of Comparative Embryology Studies

In all vertebrae species:
- Embryonic gill pouches
- Presence of a tail
- Two chambered heart


Comparative Homologous Structures

Organs that are very similar in structure but have different functions due to environmental selection pressure. Organisms possessing homologous structures that are similar are more likely to share a common ancestor


Example of Homologous Structures

Forelimb of the vertebrae


Comparative Vestigial Organs

The structures which are the remains of organs that were required in ancestral form. These organs are no longer essential. These organs suggest ancestral relationship with organisms that have functional forms of the same organs


Example of Vestigial Organs

- Nictitating membrane
- Third molars
- Appendix