Unit 8 - DNA and Protein Synthesis Flashcards
Role of Bacteria in the Discovery of DNA’s ability to transfer info.
Bacteria can change their characteristics based on their genetic info. (especially shown in Griffith’s experiment) – this showed scientists that DNA could transfer traits.
Griffith’s Experiment
Through his experiment, discovered that somehow, the heat-killed bacteria passed their disease-causing ability to the harmless bacteria.
Oswald Avery’s Experiment
Destroying proteins, lipids, carbohydrates, etc., in bacteria, the transformation opperated successfully.
However, when destroying DNA in the bacteria, this transformation stopped.
Found that DNA stores and transmits genetic information from one generation of bacteria to the next.
Hershey-Chase Experiment
Wanted to determine if DNA or proteins entered cells during infection - saw that phosphorus entered the cells meaning DNA traveled in.
Confirmed Avery’s results that DNA was the genetic material found in genes—not just in viruses and bacteria, but in all living cells.
Describe how Franklin’s, Watson’s and Crick’s work lead to the further understanding of the structure of DNA.
Using X-ray diffraction, Rosalind Franklin noticed that the image of DNA was an “X”-shaped pattern, suggesting that strands of DNA are twisted around each other, taking on a helix shape.
Watson and Crick then used Franklin’s X-ray image of DNA to build a model that explained the specific structure and property of DNA.
3 parts of a nucleotide
phosphate group, deoxyribose (sugar), nitrogenous base
Function + Structure of DNA
Stores, copies, and transmits the genetic information in a cell.
Double-stranded helix (strands are antiparallel)
Made of nucleotides
Semi-conservative - each new DNA molecule consists of one original strand and one newly synthesized strand, conserving one half of the original DNA molecule
Covalent Bond
Connects the nucleotides within the same strand.
Hydrogen Bond
Connects the nucleotides from one strand to the other strand.
Steps of DNA Replication
Helicase “unzips” DNA.
hydrogen bonds between base pairs are then broken.
DNA polymerase joins individual “free” nucleotides to produce a new strand of DNA.
DNA polymerase then “proofreads” each new DNA strand, so that each molecule is a near-perfect copy of the original.
Functions of the key components of replication
Helicase - enzyme which brakes the hydrogen bonds
DNA polymerase - enzyme that adds in the “free” nucleotides and “proofreads” the copied strand, ensuring accurate replication
Free nucleotides - detached nucleotides found in nucleus
Parts of RNA nucleotide
Phosphate Group
Ribose
Nitrogenous Bases
mRNA
- messenger RNA
Function: Carries the trabnscribed “copy” of DNA instructions (since it can leave the nucleus) to make proteins.
tRNA
- transfer RNA
Function: bring amino acids to the ribosome to make proteins
rRNA
- ribosomal RNA
Function:
What helps make up the ribosome - part of ribosome that reads the mRNA sequence
RNA Polymerase in transcription
Constructs RNA molecules using DNA as a template.
Steps + purpose of transcription
Purpose: Process of transcribing DNA into mRNA in the nucleus so it can leave the nucleus to enter the cytoplasm to make proteins.
DNA is “unzipped” by RNA polymerase.
One strand of DNA is transcribed at a time (where RNA polymerase reads each nucleotide of DNA and attaches the complementary RNA bases - with help - to this DNA strand).
The end of this process results in mRNA is created (which can then leave the nucleus).
What are the monomers of proteins?
Amino Acid
Steps + purpose of translation
Purpose: mRNA is “read” by the ribosome to make an amino acid (polypeptide) chain, and eventually a protein.
- Ribosomes read the mRNA sequence 3 bases at a time (AKA a codon at a time)
- The process begins with an mRNA codon of AUG that codes for “start”, or the methionine amino acid.
- tRNA brings the proper amino acid to the ribosome, which attaches the amino acids to make the amino acid (polypeptide) chain.
- Each tRNA carries a specific amino acid. The tRNA anticodon (3 base pairs) pairs with the mRNA codon.
- The ribosome continues to build the chain until a “stop” codon is read.
(just a signal) -where the chain folds into a protein
Codon
- group of 3 nucleotides on mRNA
- Each codon codes for a specific amino acid
Mutation
Heritable changes in genetic information which can affect the protein in different ways.
Point Mutation (substitution)
changes to a nucleotide at a single point in the DNA sequence
Substitution - one base in the nucleotide is changed to another base. (EX: CCC changes to ACC)
Frameshift Mutations (deletion, insertion)
mutations that shift the “reading frame” of the DNA.
Insertion - one nucleotide is inserted into the DNA sequence
Deletion - one nucleotide is removed from the DNA sequence
anticodon
three-nucleotide sequence in tRNA that corresponds with the codons of mRNA.
