Genetics & Evolution

Species (definition

Group of organisms that can interbreed to produce fertile offspring

What are the two types of variation?

Acquired. Inherited

What is acquired variation? Example?

Not inherited but developed during life e.g. Ability to ride a bike

What is inherited variation? Example?

Controlled by genes e.g. hair colour

Heredity (definition)

Passing on of features from parents to offspring by means of genes

What to things are chromosomes made of?

DNA. Protein

Function of protein in chromosomes

Holds DNA in tightly packed way inside the nucleus of the cell

What does DNA consist of?

Coding DNA. Non-coding DNA

What is non-coding DNA?

Has no genes and cannot code for the formation of proteins.

Function of non-coding DNA

Highly variable parts of it are used for DNA profiling

Draw a diagram of a chromosome

…

Genes (definition)

Section of DNA that codes for a particular protein.

Allele (definition)

Alternative forms of the same gene. You get two genes for each trait

Gene expression (definition)

Process of changing the information in a gene into a protein. It is the expression of genes that produces the traits inherited.

What does DNA stand for?

Deoxyribonucleic acid

What is DNA?

Hereditary material for all living organisms

Where is DNA found?

On chromosomes

Shape of DNA

Double helix

What are the two strands of DNA linked with?

Chemicals called bases

What does a pair of bases form in DNA?

A rung

Name the four bases of DNA?

Adenine. Thymine. Guanine. Cytosine

What base does Adenine join with?

Thymine

What base does Guanine join onto?

Cytosine

What A/T and G/C known as?

Complementary base pairs

What kind of bonding are base pairs held with?

Hydrogen bonding

Double-stranded DNA is …. to form it’s double helix shape?

Twisted

Draw a nucleotide

…

What two scientists worked out the structure of DNA?

James Watson & Francis Crick

Name the sugar found in DNA

Deoxyribose

Name the three parts in a nucleotide

Phosphate group. Deoxyribose. Nitrogen-containing base

What is the two types?

Purines. Pyrimidines

What is a purine base?

Double-ring molecule

What is a pyrimidine base?

Single-ring molecule

Which of the four bases are purine?

Adenine. Guanine

Which of the four bases are pyrimidines?

Thymine. Cytosine

Genetic code (definition)

The sequence of bases in DNA that provide the instructions for a cell to for, a protein

How many amino acids in one chain?

Over 200

Name of the three consecutive bases in DNA used to form an amino acid

Triplet or codon

Explain DNA replication

Double helix unwinds. Bonds between base pairs are broken. Strands of the double helix separate. DNA bases in the cytoplasm enter nucleus. Incoming bases attach to complementary bases. Each side acts as a template for the new DNA. Each rewinds, and a new helix is formed

What breaks the bonds between base pairs in DNA replication?

Enzyme

Why is DNA replication important?

Since DNA is able to produce exact copies of itself it lets the same DNA be passed on to new cells during mitosis

Genetics engineering (definition)

The artificial manipulation or alteration of genes

Name the five processes of genetic engineering

Isolation. Cutting. Insertion. Transformation. Expression

Explain isolation

Remove both DNA from the human (contains wanted gene) and cloning vector (plasmid from bacteria)

Explain cutting

Human DNA and plasmid DNA treated with the same restriction enzyme. Cut DNA only at certain sites

Why is the same restriction used for both samples of DNA?

In order for the cut ends to be complementary

What enzyme is used to combine DNA from the sources?

DNA ligase

What kind of enzyme is DNA ligase?

Anabolic enzyme

Explain insertion/ligation

Target gene placed into DNA of host. DNA ligase used to combine.

Explain transformation

Plasmid with human gene placed back into bacteria

Explain Expression

Getting bacteria to produce the wanted product

Applications of genetic engineering examples

Vitamin A in rice. Sheep produce clotting factor. Bacteria make insulin

Explain vitamin A in rice (genetic engineering)

Vitamin A deficiency in Asia. Rice is a staple of their diet doesn’t produce vitamin A. Vitamin A taken from daffodils and inserted into rice grains.

What does G.M stand for?

Genetically Modified

Explain sheep producing human clotting factor

Haemophiliacs can’t produce a clotting factor (their blood fails to clot). Human gen inserted into DNA of sheep. Clotting factor produced in their milk

Explain how bacteria make insulin (genetic engineering)

Human gene for insulin inserted into bacterium. Bacterium produces large quality of insulin. People with diabetes can inject themselves

Ethical issues of genetic engineering

Release of GMOs into the environment. GMOs as a good source. Animal welfare

Example the release of GMOs into the environment

If gene for weed killer resistance transferred to weed plants, result in uncontrolled growth of weeds

Example of GMOs as a food source

Eating animal genes contained in food plants would concern vegetarians

Example of animal welfare

Use of growth hormones in animals may cause limb deformation and arthritis

Genetic Screening (definition)

Testing DNA for the presence or absence of a particular gene or an altered gene

Explain adult screening

Screening carried out on adults who may carry a defective gene in each of their cells. People get information on the chances of having a child with a disorder or prépa for a disease that might affect them

Embryonic or foetal screening

Cells removed from the embryo, placenta, or fluid around foetus. Cells tested to detect any genetic disorder

Name genetic disorders (4)

Albinism. Haemochromatosis. Cystic fibrosis. Cancer

Explain albinism

Pigment melanin not be made

Explain haemochromatosis

Too much iron accumulates in the body and has to be removed by regular bleeding

Explain cystic fibrosis

Build up of mucus in the lungs and intestine

Differences between DNA and RNA (DNA)

Bases are ATCG. Double-stranded. Found in nucleus

Differences between DNA and RNA (RNA)

The bases are AUGC. Single-stranded. Found in nucleus and cytoplasm

What is the U base in RNA?

Uracil

How many different types of amino acids are there in the cytoplasm

20

What are the two processes of protein synthesis?

Transcription. Translation

Transcription (definition)

Rewriting the code from DNA to RNA

Where does transcription occur?

Nucleus

The bases in DNA work in groups of …

Three

What do the enzymes in the nucleus do in transcription?

Unwind DNA double helix

What happens when strands are separated in the nucleus?

RNA bases enter nucleus and bond with one of the exposed DNA strands. RNA bases join together to form mRNA

What enzyme joins RNA bases together?

RNA polymerase

What kind of enzyme is RNA polymerase?

Anabolic

Why is the genetic code to make a protein copied from DNA to mRNA?

DNA can’t leave the nucleus

What does each mRNA strand carry?

Start codon. Series of codons for particular amino acids. Stop codon

What is a stop codon?

Where the protein chain ends

Translation (definition)

Production of a protein according to the RNA code

Where is ribosomal RNA found (rRNA)?

Ribosomes of the cell

Function of rRNA

Bind mRNA to the ribosome

Where does the mRNA move from to?

Nucleus to cytoplasm

What attaches to the mRNA?

Ribosomes

Where is the site of protein synthesis?

Ribosomes

What are ribosomes?

Special decoding device ensuring that the amino acids are assembled in the correct sequence as instructed by the genetic code on the mRNA.

What does the cytoplasm supply the ribosome with?

tRNA (Transfer RNA)

What does each tRNA molecule have attached to them?

Anticodon and a specific amino acid on the other end

What is an anticodon?

Special triplet of bases

Where will the first tRNA molecule attach on the mRNA?

Just after the start codon

How do the tRNA molecules attach to the mRNA?

Two at a time, bringing their particular amino acid with them

Each amino acid type has its own particular …

Anticodon

What happens to the amino acids connected to the tRNA after the tRNA attaches to the mRNA?

Detached from tRNA and bonded together by ribosome to form part of the protein chains

tRNA molecules will continue to bind until a … is reached.

Stop codon

What happens to the chain of amino acids after it's made?

Protein is folded

What is the result at the end of translation in protein synthesis?

New protein is formed

DNA Profiling (definition)

Method of making a unique pattern of bands from the DNA of a person. Which can then be used to compare with the DNA profile of another person.