Molecular Genetics Flashcards
What is DNA for?
-A molecule that carries genetic information, which is used to synthesize specific polypeptides.
Describe the structure of a DNA in terms of the bases, sugar and phosphate groups found in each of their nucleotides.
I GOT THIS FROM THE BIO WORKSHEET CORRECTIONS I DID BUT IDK LOL
A DNA is made up of 2 anti-parallel strands of polynucleotides that coil to form a double-helix structure. Each chain is a polymer of many nucleotides linked together. Each nucleotide is made up of a deoxyribose sugar linked to a phosphate group and a nitrogenous base. There are 4 types of nitrogenous bases namely adenine, thymine, guanine and cytosine. The bases are paired together by hydrogen bonds. This pairing is known as complementary base pairing where adenine always binds to thymine and cytosine always binds to guanine.
What is the rule of base pairing?
- Adenine (A) bonds with thymine (T)
- Guanine (G) bonds with cytosine (C)
- These pairs of bases are called complementary bases. I like to call it ATGC for All The Good Cats.
- Ratio of A:T in the DNA will always be 1:1, likewise for G:C.
Describe the relationship between a gene, a DNA and a chromosome.
- A gene is a segment of DNA made of a sequence of nucleotides that codes for the synthesis of a single polypeptide.
- Each DNA molecule consists of 2 anti-parallel strands twisted around each other to form a double helix.
- A molecule of DNA is wrapped around proteins to form a single chromatin thread.
- During cell division, the chromatin threads coil more tightly to form chromosomes inside the nucleus.
What is a gene made of?
A gene is a sequence of nucleotides, as part of a DNA molecule.
State an example of gene mutation.
(1) Albinism - mutation in the gene causes an absence or defect in the enzyme that produces the pigment melanin.
(2) Sickle-cell anemia - mutation in the gene causes the protein product to differ from the normal protein by a single amino acid, causing red blood cells to become sickle.
What is transcription?
-Transcription is the synthesis of mRNA from a DNA template.
What is translation?
Translation is the process where ribosomes synthesize proteins using the mature mRNA strand transcript produced during transcription.
- Translation starts with an mRNA attaching to a ribosome.
- A start codon AUG starts the process and amino acids are continually attached until the ribosome reaches the stop codon on the mRNA.
- Upon encountering the stop codon, translation stops, the ribosome leaves the mRNA, and a complete polypeptide is produced.
Difference between DNA and RNA
DNA ; RNA
(1) Responsible for storing and transferring genetic information ; Directly codes for amino acids and acts as a messenger between DNA and ribosomes to make proteins
(2) Deoxyribose sugar ; Ribose sugar
(3) Double-stranded ; Single-stranded
(4) Nitrogenous bases A:THYMINE ; A:URACIL
(5) Longer chain of nucleotides ; Shorter chain of nucleotides
(6) Ratios of A:T, G:C = 1:1 ; No fixed ratio
(7) Always present ; Only made when needed
What is genetic engineering?
- Genetic engineering refers to the manipulation of an organism’s genetic material
- It involves the transfer of genes from one organism to another
- Done using a vector molecule
What is a vector molecule?
- A vector molecule is a DNA molecule that is used to carry a gene or genes from one organism to another
- Plasmids (circular DNA) from bacteria are commonly used as vectors.
- U just got vectored insert meme here
Explain how a gene that controls the production of human insulin can be inserted into bacterial DNA to produce human insulin in medical biotechnology.
Cut out the desired gene from the human insulin gene using a restriction enzyme. Cut out the plasmid from a bacterium using the same restriction enzyme. This produces sticky ends complementary to the ends of the gene that can join together.
Mix the plasmid and gene. They are able to bind as the restriction enzyme cuts both in the same way. Add DNA ligase to seal them together. This is now called a recombinant plasmid.
Insert the recombinant plasmid into bacterium by applying temporary heat or electric shock to open up pores in the cell surface membrane of the bacterium for the plasmid to enter.
In order to produce large amounts of human insulin, large amounts of transgenic bacteria needs to be cultured. The bacteria are placed in large steel tanks called fermenters under optimal conditions for growth and reproduction. Features of a fermenter include a nutrient broth, cooling jacket, pH controller and aeration system.
At the end of fermentation, the bacteria cells are lysed open. Insulin is extracted and purified by crystallization.
State an application of genetic engineering.
- Creation of transgenic plants that are resistant to herbicides
- Creation of transgenic plants that are pest-resistant
- Gene therapy – Healthy genes from a person can be transferred to the cells of another person with defective genes
Compare the differences between selective breeding and genetic engineering.
SB ; GE
Organisms must be closely related ; Genes from an organism can be inserted into non-related species or different species
Possibility of defective genes being transmitted to offspring ; Selection of genes b4 transfer = no risk of defective gene
Slow process involving several generations ; Individual cells can reproduce rapidly in a small container in a lab
Less efficient, grows slower and requires more food ; More efficient, grows faster, requires less food.
What are some benefits that genetic engineering can bring to society?
- Low cost production of medicines - Drugs like human insulin become more affordable.
- Production of crops that grow in extreme conditions - Crops can be grown in environmental conditions that are not favourable for cultivating most crops.
- Development of pesticide-resistant crops - Use of costly pesticides that may damage the environment is reduced.
- Development of foods designed to meet specific nutritional goals - Nutritional quality of food is improved.
