Genetics and Molecular Biology Flashcards
Nucleic Acid
Macromolecules that contain genetic information for protein synthesis.
Nucleic acid structure
1.) Phosphate group- Neg charged oxygen atoms bonded to it
2.) Pentose molecule- Ribose or deoxyribose
3.) Nitrogen base- Can give molecules to carbon, hydrogen, and oxygen
Who discovered nucleic acids?
Friedrich Miescher- From the white blood cells contained in pus he got from used hospital bandages.
Gene expression
Process of using the information in a gene to create a protein inside a cell.
Proteins
Macromolecules that direct all structures and functions of the cell, allowing gene regulation to be tightly controlled.
Steps for gene expression
- Transcription
- mRNA processing
- mRNA export
- Translation
- Protein folding
- Protein translocation
Splicing
Process where introns are removed from the transcript, and the remaining exons are attached back together.
Introns
Non-coding sections of the mRNA
Exons
The remaining coding sections of mRNA
Alternative splicing
mRNA can be sliced in different ways to create different proteins
Stop codon
Signals for translation to stop
Ways that gene expression is regulated
- Transcription factors
- Stability of mRNA
- Alternative splicing
- Post-transcriptional regulation
- Post-translational modifications
Ways to measure gene expression
-Western blot
-Immunofluorescence
- Microarray
- RT-PCR
- In situ hybridization
Insertion mutation
Additional nucleotides are inserted into the DNA
Complementary base pairs
Adenine–Thymine (RNA it is uracil)
Cytosine–Guanine
Frameshift mutation
All of the codons downstream from the mutation are changed
Causes of insertion mutation
- By chance during errors in DNA replication
- By chemicals or radiation
Examples of insertion mutation
- Fragile X syndrome
- Huntington’s disease
-Myotonic dystrophy - Cystic fibrosis
Deletion mutation
When a nucleobase is removed from the DNA sequence
Substitution mutation
When a nucleobase is substituted for another nucleobase.
Duplication mutation
When a section of the DNA sequence is repeated
Causes of deletion mutation
- Translocation
- Unequal chromosome crossovers
Types of deletion mutations
- Point mutation (affects a single nucleobase)
- Frameshift mutation (when one deletion shift all nucleobases in the reading frame)
- Chromosome deletion (An entire missing piece of a chromosome)
Restriction enzymes (endonucleases)
Proteins that recognize and cleave specific DNA sequences. Found only in bacteria.
Werner Arber
Discovered restriction enzymes in the 1960s
Hamilton Smith
Reproduced Arber’s results, and named them
Dan Nathans
Used the work of Arber and Smith to pioneer the field of molecular biology and genetics
EcoR1 works by… (3 steps)
1.) EcoR1 (a restriction enzyme) recognizes DNA sequence GAATTC, and loosely binds to it.
2.) EcoR1 active site closes and binds more tightly forming a kink in the viral DNA.
3.) When kink is in right orientation, active site binds even more tightly until it cleaves the 5’ and 3’ DNA sequence between G and A.
Restriction enzyme rules (3)
- Cleavage site sequences are usually palindromic (reads the same forward as backwards)
- After cleavage, restriction enzymes leave sticky ends
- Most restriction enzyme cleavage sequences are 4-6 bases long
Main usage of restriction enzymes in molecular biology
Construct plasmids that can express specific gene products in a cell. After cutting the gene fragment, the gene can be amplified and then purified.
5 types of restriction enzymes
I- Cut DNA far from the recognition sequences
II- Cut at specific positions closer to or within the restriction sites; most common type and used for DNA analysis and gene cloning
III- Multifunctional proteins with the subunits Res and Mod
IV- Know to cleave methylated DNA and use recognition sequences similar to II
V- Made up of dimers, require magnesium as a cofactor, and uses an RNA guide sequence instead of DNA. Used for CRISPR
DNA polymerase
When DNA separates during replication, a special protein known as DNA polymerase comes in and adds in the new nucleotides.
Polymerase Chain Reaction (PCR)
Used to make many copies of a DNA sample in the lab.
Recombinant DNA
DNA that is cut and pasted together from multiple sources.
Two-step process for recombinant DNA technology
1.) Restriction enzymes to cut through the double helix of bacteria.
2.) DNA ligase to paste the separate pieces of DNA back together.
Applications of recombinant DNA
- GMOs
- Disease research
Stanley Cohen and Herbert Boyer applied for a patent for…
Recombinant DNA technology
