DNA and protein synthesis
Terms in this set (60)
DNA and RNA are in which group of molecules?
Function of DNA?
1. Store genetic information
2. provide instruction for protein synthesis
3. Pass genetic code to daughter cells
General function of RNA?
Carry out instruction from DNA for protein synthesis.
Function of mRNA?
To make a copy of DNA and carry this copy from the nucleus to the cytoplasm so that this information can be used to make a protein.
Function of tRNA?
To transfer amio acids to ribosomes for protein synthesis.
Function of rRNA?
To control ribosome formation in the cytoplasm.
What are the 3 types of RNA?
mRNA, tRNA, rRNA
Name of monomer that makes up nucleic acids?
Components of nucleotides?
Nitrogenous bases found in DNA?
Adenine (A), Guanine (G), Cytosine (C), Thymine (T)
Nitrogenous bases found in RNA?
Adenine (A), Guanine (G), Cytosine (C), Uracil (U)
Complementary base pairing?
When nitrogenous bases join with a hydrogen bond A goes with T and G goes with C. In RNA, A goes with U.
Major differences between DNA and RNA
DNA - double helix RNA - straight
DNA - deoxyribose sugar RNA ribose sugar
DNA - thymine RNA - Uracil
DNA - double strand RNA - single strand
DNA - very long RNA - short
Process whereby a DNA molecule makes an exact replica of itself before cell division.
Why must DNA replicate?
Each daughter cell must receive an exact copy of the DNA from the parent cell.
Where and when does DNA replicate?
In the nucleus during interphase. Interphase is the stage before mitosis occurs.
What are the steps of DNA replication?
1. The enzyme helicase "unzips" the DNA molecule from one end breaking the H bonds between the nucleotides.
2. Each strand acts as a template for the production of the other side
3. Complementary base pairing occurs as template nucleotides bond to complementary nucleotides by H bonds.
4. Enzyme DNA polymerase facilitates the new double strand to have all phosphate and sugars bonded. The DNA polymerase facilitates adding in the complementary bases in a continuous daughter strand to the 3' end of the strand. On the 5' strand the DNA polymerase synthesizes the daughter strand in pieces.
5. DNA ligase links the individual pieces of the daughter strand together so that they are continuous.
Why is DNA replication called "semi-conservative?
Because each daughter molecule conserves 1/2 of each parent DNA molecule.
What is recombinant DNA?
DNA that is removed from one organisms and combined with the DNA of another organism.
What is a plasmid?
A simple ring of DNA found in bacteria. It can be used for creating recombinant DNA.
Process of creating recombinant DNA?
Restriction enzyme is used to cut open the plasmid. The DNA from a cell containing a gene of interest is isolated and inserted into the plasmid. The plasmid is put back into the bacterial cell and allowed to multiply with the gene of interest. This gene is then place in an organism where it is wanted, for example in a plant to create a pest resistant plant.
What are some examples of uses for recombinant DNA?
1. Treatment of cystic fibrosis.
2. Cancer treatment
3. Creation of pest resistant plants.
4. Creation of plants that have a higher nutrition level.
5. Production of hormones such as insulin and growth hormones.
An organism that has been modified with genetic material from another species. eg. genetically modified crops
Examples of genetically modified organisms?
1.Golden rice contains daffodil genes which produce Beta carotene (Vitamin A)
2. Transgenic goats have been created by inserting the a human gene so that the milk they produce contains an antibacterial enzyme found in human milk. This could then be used for human consumption so that the milk they drink prevents intestinal infections.
Exact genetic copies of organisms that in some cases can be created artificially. For examples, scientists have created clones of sheep.
Two major steps in protein synthesis?
Transcription and Translation.
The process of creating the mRNA from the DNA template.
Where in the cell does transcription take place?
In the nucleus.
The process of creating a polypeptide (protein) from the mRNA transcript.
Where in the cell does translation take place?
In the cytoplasm at a ribosome.
Role of ribosomes in protein synthesis?
To control the synthesis of polypeptides at site. Ribosomes are made up of protein and rRNA.
The steps of transcription?
1. Initiation: a promoter nucleotide sequence signals the start of transcription. RNA polymerase enzyme attaches to the promoter to start mRNA synthesis.
2. Elongation: Individual complementary mRNA nucleotides bond together to form a single mRNA strand.
3. Termination: RNA polymerase reaches a base called a terminator. mRNA is released from the DNA template.
An enzyme that aids in transcription.
How is the sequence of bases in a DNA molecule used to determine the sequence of amino acids in a protein?
Each each set of 3 bases in a DNA molecule codes for a specific amino acid.
What is a codon?
The sequence of bases on mRNA molecule the codes for a specific amino acid.
How many different amino acids are there?
Why are the codes for bases in sets of 3 and not sets of 2?
If the bases were in sets of 2 that would only create 16 possible codes (not enough to code for the 20 amino acids that exist).
If the DNA code on the template strand is TACTCGACCGGCAATATC, what will be the sequence of bases on the transcribed mRNA molecule?
If the RNA sequence is AAA-AUU-UAG, what was the original DNA sequence.
If the DNA sequence is TAC-TCC-ACA-ATC, what is the sequence of amino acids in the polypeptide?
Met (or start)- Arg - Cys - Stop
Role of tRNA in translation?
To carry the amino acid to the ribosome, where the codon is matched with the anticodon.
Role of mRNA i translation?
To provide the codons that determine the sequence of amino acids.
Role of ribosomes in translation?
Provide the site of protein synthesis where mRNA and tRNA can match codon with anticodon.
Composition of ribosome for translation?
Composed of small subunit and large subunit. The large ribosomal subunit contains binding sites for the tRNA molecules to attach.
Steps in translation?
1. Each amino acid attaches to its proper tRNA.
2. Initiation - The mRNA, the first tRNA and the ribosomal subunits come together.
3. Elongation - a succession of tRNAs add their amino acids to the polypeptide chain as the mRNA is moved through the ribosome one codon at a time.
4. Termination - the ribosome recognizes a stop codon. The polypeptide is terminated and released.
What is an anticodon?
The three base code on a tRNA that has a complementary codon on the mRNA.
If the condon is UCA what is the complementary anticodon on tRNA?
Poly = many ribosomes translating at the same time off the same mRNA.
How can mutations in DNA change the sequence of amino acids in a polypeptide chain?
If the sequence of nitrogenous bases in DNA are copied incorrectly during DNA replication then then DNA will not have the correct code for building a polypeptide chain with the correct amino acids.
What is an example of a disease caused by a mutation in the DNA sequence?
sickle cell anemia?
What is sickle cell anemia?
Because DNA is copied incorrectly during DNA replication, DNA codes for the wrong amino acids in the protein hemoglobin. As a result the red blood cells have an abnormal shape (sickle-shaped) and the person fells fatigued, is anemic, can have heart failure, brain damage etc.
What change in DNA causes Sickle cell anemia?
One base in the DNA sequence is changed from CTT to CAT when the DNA is replicated. As a result the amino acid glumatic acid is replaced by valine in the hemoglobin molecule in blood.
Point mutations involve a single nucleotide being added or deleted in a base sequence and therefore cause a change in a specific codon.
What is base substitution?
Point mutation when one nucleotide base is copied incorrectly in a DNA sequence.
What is base deletion?
Point mutation when one nucleotide base is missing when DNA is copied.
Which type of point mutation causes more problems, substitution or deletion?
Deletion because it results in change to all amino acids from the point of the mistake and on. Substitution causes a mistake in only one amino acid.
A mutation which occurs during DNA replication or recombination (no external agent/.
What is a mutagen?
A physical or chemical agent that causes a mutation.
What are some examples of environmental mutagens?
1. Radiation - ultraviolet, x-rays, nuclear radiation
2. Chemical carcinogens eg tobacco, chemicals, pesticides, PCBs
3. Viruses - eg HPV virus causes cervical cancer.
Type of bond found between base pairs?
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THIS SET IS OFTEN IN FOLDERS WITH...
DNA and Protein Synthesis
Frontiers of Biotechnology
Chapter 8 Recombinant DNA Technology