Biotechnology and evolution

Selective breeding

Allowing only those animals with desired characteristics to produce the next generation (has been practiced over thousands of years)

What are the two types of selective breeding?

Hybridization and inbreeding

Hybridization

Crossing dissimilar individuals to bring together the best of both organisms.

Inbreeding

Crossing individuals w similar characteristics

What does inbreeding allow?

* allows the unique characteristics to be kept
* Increases susceptibility to diseases and deformities

Increasing variation

By introducing mutations (source of genetic mutation)

How are genetic mutations done?

By exposing organisms to radiation/ chemicals (used on plants and bacteria)

Manipulating DNA

They use their knowledge of the structure of DNA and its chemical properties to change the DNA molecules. Different techniques are used to cut and extract, identify the diff. sequences of DNA and make more copies of DNA.

Genetic engineering

Changes in DNA

Steps of creating recombinant

1. Extract DNA
2. Isolate the gene for insulin using a restriction enzyme (cuts DNA at a specific sequence)
3. Creates sticky ends: single strands of DNA produced from the restriction enzyme
4. Extract a ring of DNA: plasmid from a bacterial cell
5. Cut the plasmid with the same restriction enzyme to cut the same sequence
6. Human gene and plasmid combine using DNA ligase
7. Insert recombinant DNA into bacterial cell.

Biotechnology

The manipulation of organisms or their components to make useful products.

Where is biotechnology used?

This is used in DNA technology; modern laboratory techniques for manipulating genetic material.

* modify specific genes
* move genetic info between organisms

Recombinant DNA

scientists combine pieces of DNA from 2 different sources (mostly different species) to form 1 single DNA molecule.

Where is Recombinant DNA used?

This is used for genetic engineering: the direct manipulation of genes for practical purposes.

* scientists use genetic engineering on bacteria to mass produce a variety of useful chemicals.

plasmids

small + circular DNA molecule that duplicates separately from larger bacterial chromosomes.

* typically carry a few genes and pass them down
* they are easily manipulated, they can carry any gene

Where are plasmids used?

They are used in gene cloning

gene cloning

the production of many identical copies of gene-carrying DNA

* important to genetic engineering.

Restriction enzymes

Cutting tools of bacterial enzymes

* each different enzymes focuses on a different short sequence (restriction site)
* the same restriction enzyme cuts the same restriction fragments from the different DNA
* these fragments can be put back together using DNA ligase

Genomic Library

a collection of cloned DNA fragments that include an organism’s entire genome

bacteriophages

Viruses that infect bacteria can serve as vectors in cloning.

* when used as a vector, the DNA fragments are inserted into phage DNA molecules
* this recombinant phage DNA can be put back into a bacterial cell through a normal infection process
* The DNA is then replicate
* we use different restrictive enzymes for different recognition sites.

Polymerase Chain Reaction

* widely used in molecular biology
* makes millions/billions of copies of a specific DNA
* allows scientists to study a large amount of DNA from a small sample

DNA finger printing

* Gel + Electricity
* A technique used by forensic scientists to identify individuals by characteristics in their DNA

Gel Electrophoresis

method used to separate + analyze macromolecules ( DNA + RNA + proteins) based on size and electric.

Transgenetic organisms

Contain genes of another organism GMO

* have been used to study genes + improve supply
* livestock have been produced w extra copies of growth hormone genes
* chicken that has resistance to bacterial infections cause food poisoning

steps of cloning

1. donor being cloned: harvest one somatic cell → remove nucleus ( 46 chromosomes)
2. donor egg cell: remove nucleus → egg is empty
3. inject donor somatic cell nucleus → egg is empty
4. newly fused egg divides by mitosis → creates embryo
5. embryo placed into uterus

evolution

* Gradual change in a species over time
* is the process of descent w modification

Charles Darwin

all species over time have descended from a common ancestor. The pattern of evolution from natural selection

Darwins Voyage

* 5 year voyage as a naturalist
* collected flora, flauna, fossils
* reads scientific books + articles
* returns to England and studies

fitness

The ability of an individual to survive and reproduce in an specific environment

adaptations

helps an organism survive and reproduce

what does natural selection result in?

results in changes in the traits of the population. Increases their fitness + survival.

Natural Selection

Process where the individuals become better adapted to their environment and become more likely to survive + reproduce.

4 factors of natural selection

* overproduction
* competition
* variation
* selection

overproduction

produce more offspring to survive

competition

food space

variation

differences between individuals within the species

selection

the environment selects the organism with the best traits/adaptation for the future

Lamarks theory of evolution

* selective use or disuse of organs


* traits are acquired
* lost during an individuals lifetime

hutton + Lyell

The earth is billions of years old. The processes that change the Earth in the past are the same as now.

Thomas Malthus (principle of population)

human population will grow faster than the space ; food supplies given

Darwin ‘s book Title?

The Origin of Species

evidence of evolution

* comparative anatomy
* fossil record
* geographical distribution of living species
* comparative embryology
* comparative biochemistry

comparative anatomy

* homologous structure
* analogous structure
* vestigial structure

homologous structure

similar structure but different function (common ancestor)

analogous structure

similar function but different function ( NO common ancestor)

vestigial structure

remnants of features that served important functions in organism’s ancestors

Fossil Record

Fossils: remains of an organism that have been preserved by natural processes

* many different types of fossils ( petrified in stone, ice, tar, amber)
* gaps in fossil record
* provides evidence of evolution
* by using time + location
* absolute dating: using radioactive isotopes to look at the half-life of radioactive materials

geographical distribution

* similar animals in different locations were the product of evolutionary descent
* made possible by Pangea

comparative embryology

similarities in embryology ( early stages) show a common ancestry

comparative biochemistry (most significant)

* less amino acid differences -. the closer relation
* shows common ancestry
* molecular clock: predicts the rate of mutations every 10000 years

result of comparative biochemistry

regular evolution → modern evolution

Modern evolution

Darwin’s hypothesis: all life forms are related (molecular biology proves this)

* all forms of life use DNA + RNA
* RNA triplets are translated into amino acids (universal)
* a change in allele frequency over time

allele

different forms of a gene

population

a large group that can mate and produce fertile offspring

gene pool

all of the different genes in a population

heterozygous

dominant + recessive

homozygous dominant

purebred of dominant allele

homozygous recessive

purebred of recessive allele

allele frequency

\# of times the allele occurs in a gene pool compared to the total # of alleles for the gene

phenotype

outward appearance of an individual

genotype

the actual genetic makeup

single gene trait

a trait controlled by a single gene

polygenic traits

a trait controlled by several genes

Hardy Weinberg equation (equillibrium)

* there is a large population
* no gene flow between populations
* no mutations
* random mating
* no natural selection

environment affects the rate of evolution

* minimal change in environment = stable environment
* rapid change in environment = unstable population

3 main causes of evolution

* natural selection ( mutation/variation)
* genetic drift
* gene flow

genetic drift

* similar principles to natural selection
* more focused on mutations/random changes
* 2 types
* bottleneck effect
* founder effect
* \

bottleneck effect

overhunting + habitat destruction

founder effect

a portion of the population leave to create a new population. There can also be a barrier to divide the population.

How is the Hardy Weinberg used?

It is used to estimate how many people carry the alleles for certain inherited diseases

Different types of Natural Selection

* Stabilizing Selection
* Directional Selection
* Disruptive Selection

Stabilizing Selection

favors intermediate phenotypes

Directional Selection

Shifts the overall makeup of the population, by going against one extreme

Disruptive Selection

Environment favors individuals at both ends of the phenotypic range.

What is a species?

* Biological species
* reproductive isolation
* 2 distinct species interbreed and create hybrids

biological species

* a group of populations whose members have the ability to interbreed and produce fertile offspring

reproductive isolation

prevents gene flow, creates a boundary between species

reproductive barriers

* prezygotic (before mating)
* post zygotic (after mating)

prezygotic barriers

* habitat: lack of opportunity for mates to meet
* temporal: breeding at different times/seasons
* behavioral: failure to send/receive signals
* mechanical: physical compatibility of reproductive
* gametic: incompatibility of eggs + sperm

post zygotic

* reduced hybrid viability
* reduced hybrid fertility
* hybrid breakdown

allopatric speciation

the initial block to gene flow may come from a geographic barrier that isolates a population.

ex: mountains, canyons, lakes, movement of continents