Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
26 Cards in this Set
- Front
- Back
|
Who discovered DNA and How?
|
Johann Friedrich Miescher
Pus Cells |
|
|
Nucleotides made of
|
a phosphate group, a 5 C deoxyribose sugar, and a nitrogen base
|
|
|
4 types of Nitrogen bases
|
AGCT
|
|
|
Griffith experiments
|
Exposing mice to pneumonia. Rough and smooth. The smooth strain was the harmful strain. Rough was the not harmful strain. DNA is responsible for the characteristics of organisms. 1928
|
|
|
Watson and Crick’s model (1958):
|
Founder of the structure of DNA (double helix)
|
|
|
DNA replication and repair:
|
Hydrogen bonds between nitrogen bases break
DNA unwinds Occurs in the S phase of Interphase Free nucleotides bind to exposed bases forming a new strand |
|
|
DNA Repair:
|
The altered sequence strand is excised (cut) and removed
Enzymes build a new strand at the site thus “repairing” the damage |
|
|
The “languages”:
|
of DNA: Language of the nucleic acid
of RNA: Language of the nucleic acid of protein: language of the polypeptide |
|
|
mRNA to protein
|
• 3 bases on the mRNA code for 1 amino acid (1 set from 3 making a “codon”)
• Each set of three bases is called a codon • There are 64 codons possible |
|
|
Genetic Code
|
- 64 codons; only 20 amino acides. The code repeats itself (UUU & UUC code for phenylalanine)
- Code is not ambiguous – UUU codes only for phenylalanine |
|
|
Transcription:
|
Process by which message on DNA is copied onto the RNA
|
|
|
What happens in Transcription
|
a. DNA strand Unwinds
b. Complementary ribonucleotides placed along the exposed bases of the DNA to form the RNA strand |
|
|
The RNA produced undergoes modification before it is sent out into the cytoplasm:
|
a. attachment of a cap and a tail
b. RNA splicing |
|
|
3 types of RNA produced
|
mRNA, rRNA, and tRNA
|
|
|
mRNA :
|
Undergoes modification after it is produced in the nucleus
- Cap is attached - Tail is attached - Introns are spliced (RNA splicing) Extrons are pushed out into cytoplasm which assembles amino acids to make protein in amino acid pool |
|
|
tRNA:
|
- Is single stranded
- At one end is a triplet of bases called the anticodon - At the other end is a site for attachment of amino acids |
|
|
rRNA:
|
- Synthesizd in the nucleus
- Released into the cytoplasm - Hold the 2 subunits of the ribosome together tRNA has two sites on the Large subunit mRNA has one small subunit site |
|
|
What is Translation:
|
the synthesis of the polypeptide chain which the protein is being formed
|
|
|
3 Events in Initiation
|
- mRNA attaches to the smaller subunit of the ribosome
- tRNA chraged with an amino acid binds to the 1st codon on the mRNA - The larger subunit attaches to the smaller; tRNA slips into the P site of the larger subunit. |
|
|
3 Events in Elongation
|
Codon recognition, peptide bond formation (with amino acid #2 and #3), translocation (Ribosome moves 3 Codons to the right)
- a 2nd charged tRNA comes with its amino acid and pairs with the 2nd codon on the mRNA - A peptide bond is formed between the 1st and the 2nd amino acids; 1st tRNA leaves - Ribosome moves three nucleotides to the right; 2nd tRNA moves to the P site and A site is exposed; 3rd tRNA attached to the P site and the process continues |
|
|
3 Events in Termination
|
-When the ribosome reaches a UAA, UGA or UAG codon the mRNA, protein synthesis stops
- Release factors (are proteins) attach to the stop codons - Polypeptide chain is released |
|
|
Silent mutations
|
Cause no change in the protein produced
|
|
|
Missense mutations
|
Cause a change in the protein produced
|
|
|
Nonsense mutations
|
Cause a shortening of the polypeptide chain because of a stop codon being formed prematurely.
|
|
|
Plant viruses: infect plants
|
-Cannot penetrate an intact cell wall
- Use plamodesmata to move from cell to cell once infection takes place - No cure – Destroy plant |
|
|
HIV: Human Immunodeficiency Virus
|
- is a retrovirus because it is an RNA virus that reproduces using DNA
- Infects White Blood Cells |
