Genetics-DNA and RNA Flashcards
Variation def. and causes
Differences in members of the same species
Causes: Sexual Reproduction and Mutations
Mutations def. and causes
Def: Change in the structure or amount of DNA.
Causes: Mutagens
Mutagen def. and examples
Def: An agent that causes mutations
Eg. Radiation (x-ray, UV rays) and chemicals (tobacco, many drugs)
Types of mutations
Gene
Chromosome
Gene mutation What Name Causes Symptoms Treatment
What: 1 gene change
Name: Sickle cell anaemia
Causes: RBCs are curved/sickle shape, insoluble haemoglobin, RBCs clump.
Symptoms: Paleness, Weak, Organ failure/damage
Treatment: Blood transfusions
Chromosome mutations What Name Causes Symptoms
What: Large change to several chromosomes
Name: Down Syndrome
Causes: 3 of pair 21 chromome
Symptoms: Physical and mental features
Evolution def.
Results in
Proven by
The way in which living things change genetically to produce different types of living things.
Results in New species being formed.
Proved by Charles Darwin
Work of Darwin
Developed the theory of natural selection and proved evolutuion
Outline of Natural Selection
- Organisms reproduce in large numbers
- Population of organisms will increase until environment can’t support it and they start to struggle to survive.
- Organisms show inherited variations to adapt and survive the environment. Therefore survival of the fittest.
Natural selection def.
The process by which organisms who have genetically controlled characteristics adapt to their environment for survival and reproduce to pass on these characteristics to next generation for survival.
Evidence of evolution
What
How it shows evolution
Fossils-remains of something that lived years ago. Shells, bones, teeth
They show the changes to modern organisms. Therefore they must have adapted genetically to produce varied organisms to survive and adapt to their environment.
Genetic Engineering
What
Artificial manipulation of Genes.
Involves removing a target gene (eg. gene for insulin production) from one organism and inserting it into another organism.
The other organism is then used to produce loads of target genes.
Steps of Genetic Engineering
- Isolate (target gene)
- Cut (gene at specific site)
- Insert (into the other organism)
- Transform (new organism)
- Express
Genetic Engineering
Isolate
DNA containing target gene is removed. Plasmid DNA from bacteria cell is removed with a genetic probe.
Genetic Engineering
Cut
DNA and Plasmid are cut at specific sites wth restrictive enzymes
Genetic Engineering
Insert
Target gene is inserted into plasmid. Called Ligation
Genetic Engineering
Transform
Plasmid (now transformed) is placed back into bacteria cell.
Genetic Engineering
Express
Bacteria cell is used to produce copies of target gene.
Applications of Genetic Engineering
- Micro-organisms, eg. bacteria used to make insulin to treat diabetes. (human gene inserted into bacteria)
- Gene for making of protective protein for human lungs-emphysema. (sheep)
- To make weed killer resistant plants-transgenic plants.
- Gene for blood clotting for haemophiliac sufferers. (sheep)
what is needed for genetic engineering
- Source of DNA
- Cloning vector (DNA to accept target DNA, eg. bacteria plasmid)
- Restriction enzymes to cut at restriction sites.
- DNA ligase: To glue or insert the target DNA into the cloning vector
Ethics of Genetic Engineering
Making genetically modified organisms (GMOs) can cause environmental damage, animals suffer, food sources being produced could be a concern
Other names for Genetic Engineering
Genetic alteration
Genetic Manipulation
Genetic Modification
Genetic Cloning
DNA profiling
What
A method of making a unique pattern of bands from a persons DNA used to compare to another persons DNA.
Uses of DNA profiling
- Crime: in forensics to compare DNA of crime scene and victim to suspect to be able to associate a suspect with a crime.
- Medical: To identify if person is the mother/ father of a child (Paternal and Maternal cases)
- Genetic screening to test for disorders
Steps Of DNA profiling
- Released
- Cut
- Seperated
- Compared
DNA profiling
Released
Cells of DNA are released and isolated.
Can be amplified by polymerase chain reaction (PCR)
DNA profiling
Cut
The isolated DNA is cut into fragments by restriction enzymes.
DNA profiling
3. Separated
By Gel Elctrophoresis
-Place cut DNA into a gel
-Apply Electricity
-Drawing and seperating the negative DNA to one end and the positive to the other end.
-Also causes smaller DNA to move faster so seperates from the large DNA
Results: A pattern of DNA
DNA profiling
4. Comparing
Patterns collected are compared.
Genetic Screening def.
Testing a sample of DNA for the presence or absence of a particular gene or altered gene.
Genetic Screening method
Add a genetic probe to a sample of DNA that is being tested.
Results: If probe attaches-normal gene no altered gene.
If probe doesnt attach- presence of an altered gene.
Why is Genetic Screening used?
To test for genetic disorders.
eg. Cystic fibrosis, sickle cell anaemia
Genetic Screening
Who is tested
Adults: to see if they are carrying an altered gene that they could pass onto offspring.
Foetus: to see if the foetus has any genetic disorders
Ethics of Genetic Screening
- Could encourage termination of pregnancy
2. Could highlight that an individual is a carrier of a disorder causing discomfort or embarrassment.
Benefits of Genetic Screening
Gives people the chance to get info about the likely hood of them having a child with genetic disorder
What does RNA stand for
Ribonucleic Acid
Compare DNA and RNA
RNA: single stranded
DNA: Double stranded- double helix shape.
RNA sugar: Ribose
DNA sugar: Deoxyribose (5 carbon)
Bases in RNA
Adenine (A) = Uracil (U) (double hydrogen bond)
Cytosine (C) =+- Guanine (G) (triple bonded)
Bases in DNA
Adenine (A) = Thymine
Cytosine =+- Guanine (G)
What is a codon?
bases are arranged along the DNA in pairs. 3 Pairs together are called a codon.
Complimentary Pairs on DNA strand
A=T
G=+-C
What is a nucleotide
A unit on a DNA strand=
- A phosphate group
- A sugar (Deoxyribose)
- Connected to Nitrogen Base (ATGC)
What makes up the side of the DNA
Phosphate and sugar
Name the pyramid bases
Cytosine and Thymine (Y!!!)
Purine bases
Adenine and Guanine
joins with pyramid base
DNA replication
when?
what?
Occurs during interphase of a cell cycle-when cell not dividing
Raplication involves making an exact copy of a DNA strand
Steps of DNA replication
- DNA strand unwinds to expose 2 single strand DNA strands
- Bases from the cytoplasm enter the nucleus and bond with the exposed strands
- An exact copy of the original DNA is made.
Protein synthesis def.
Making of a protein by joining specific amino acids
Stages of Protein Synthesis and where it occurs
- Initiation-nucleus
- Transcription - Nucleus
- Translation - Ribosome
Protein Synthesis
Stage 1
Initiation-Nucleus
DNA is unwinded by enzymes.
DNA is exposed
Bases are arranged in threes-codons (triplets)
Protein Synthesis
stage 2
Transcription-Nucleus
Def: Rewriting of the code from DNA to RNA
1. One of the exposed DNA strand and its bases are matched up with RNA bases.
2. This new strand is called Messenger RNA (mRNA)
The strand of DNA and RNA are joined by enzyme RNA polymerase (anabolic)
What does mRNA consist of
- A start codon
- A stop codon
- Series of codons in the middle to code for the protein.
How are the strand of DNA and RNA joined together during Protein Synthesis
Enzyme RNA polymerase (anabolic)
Structure of a Ribosome
Large sub unit (top of hat)
Small sub unit (bottom of hat)
rRNa (ribosomal RNA)
Protein Synthesis
Stage 3
Translation - Ribose
Def: Production of a protein according to the RNA code
- The mRNA leaves the nucleus across the cytoplasm and enters the ribosome and enters the small sub unit.
- The start codon doen’t bind with anything, just starts/initiates the process. (Initiation)
- The mRNA binds with the rRNA in the small sub unit. This rRNA forms a weak bond with the mRNA to keep it in the ribosome.
- The mRNA enters 3 codons at a time. (Elongation)
- tRNA enters from the cytoplasm into the large sub unit
- This tRNA binds with the mRNA at the binding site.
Each tRNA consists of
- Amino acid-to make protein
2. A codon (anticodon) is specific- it matches the codon on the mRNA strand.
Protein Synthesis
After binding:
- Amino acids detach from the tRNA and leave the ribosome.
- It pulls the next amino acid with it and join to form a protein.
- This causes more codons on the mRNA to be pulled through and continue (like a conveyor belt)
- This continues until stop codon is reached.
Results: in a protein - amino acids joined together by a peptide bond.
