Download BIO120 LAB --DNA + PROTEIN SYN-

Topics
•
•
•
•
DNA organization, structure, & function
Replication
RNA
Protein Synthesis
– Transcription
– Translation
DNA Function
• genetic information
– how to build, operate, and repair cell
– Specifically how and when to make proteins
• passed from one cell generation to the next;
– From one cell to the next within an
individual
– passed from parent to child
DNA Organization
• DNA molecule = genes + “non-coding DNA)
“chromosome”
~3% of DNA
~97% of DNA
“coding”
• gene =protein instructions
• non-coding = when to activate gene/make a protein
chromosome
genes
Non-coding
• Double helix
• Two strands twisted together like a corkscrew
DNA Structure
• long chains of nucleotides
• Nucleotide = sugar + phosphate + nitrogenous base
• Sugar = deoxyribose (5C)
• 4 Different Bases: A, T, G, C
•
Bases = pyrimidines (1 ring) or purines (2 rings)
• double stranded
5’
– sugar-phosphate backbone=covalent
– base-base=hydrogen
hydrogen bond
3’
DNA Structure Cont.:
Double Helix
• Twisted=helix
covalent bond
5’
3’
‘f’-five; ‘f’ phosphate; 5’ end
DNA Structure Cont.:
Complementary Base Pairing
• 4 different bases
• Complementary pairing
– C—G
– A—T
Functional Characteristics of DNA: IMPORTANT!!
• Information = order of the bases/base sequence
– ATTGCGCA means something different then:
– ATTGCGGA
• Complementary base pairing
• Allows DNA to be copied over and over and the
information stays the same.
DNA Replication
•
•
•
•
•
•
•
Happens as part of cell cycle
In preparation for cell division
Duplicates all the DNA: 1 copy  2 copies
One copy for each cell
Semiconservative
In nucleus of cell
NOT! NOT! NOT! PART OF PROTEIN
SYNTHESIS!!!!!!!
Base Paring and Replication
A
T
A T
A T
T
A
T A
T A
T
A
T A
T A
C
G
C G
C G
G
C
G C
G C
C
G
C G
C G
G
C
G C
G C
A
T
A T
A T
T
A
T A
T A
1 copy of DNA
1 copy of
all DNA
2 copy of
All DNA
1 copy of DNA
Replication of DNA
Parent/mother cell
• Mitosis
divides/separate
daughter cells: the
each one
two copies
identical of
copy of all the
DNA: genetically identical
identical
to the mother cell
chromosomes
• Cytokinesis
divides up the
cytoplasm contents
DNA Replication
• DNA helicase “unzips” the DNA
• New nucleotides are added/paired with the
existing strands
• DNA polymerase binds the new nucleotides
together creating the P-S backbone
• Result is two identical DNA molecules (i.e.,
the base sequence is the same)
Protein Synthesis: making proteins from DNA
1. Transcription= DNA  mRNA (in nucleus)
2. Translation = mRNA  Protein (in cytoplasm @
ribosome)
mRNA
• Single stranded chains of nucleotides
• Sugar = ribose
• Bases and Pairing
– G, C, A, U replaces T
– G-C
– T-A or A-U
• Codons = 3-base groups
– One codon is a “start” codon
– Three codons are “stop codons”
–
Each codon corresponds to a specific amino acid (except stops)
2-59
Transcription
Template strand
RNA Polymerase
Coding strand
3-36
Transcription
Transcription:
from DNA  mRNA
–
promoter = how much transcription
• RNA Polymerase unzips gene and moves down DNA
– Complimentary RNA nucleotides bind DNA
– RNA nucleotides bind together (via RNA poly)
– at end of gene mRNA detaches and RNA poly detaches
• DNA zips up when transcription is done
• mRNA is made and leaves nucleus and enters cytoplasm
3-35
tRNA
• Single stranded piece of RNA
• Carried and delivers amino acids
• Anticodon binds w/ mRNA codon
3-44
Mutations, DNA, and Protiens
• Mutation = change in DNA base sequence
Change DNA
sequence
Change mRNA
sequence
Change amino acid
sequence
Change protein
Change protein
function or make
non-functional
Change codons
• change in protien  change in structure
and/or function
Mutations, DNA, and Protiens
• Mutation = change in DNA base sequence
Mutation = Δ in DNA sequence  Δ in RNA sequence/codons Δ in amino acid sequence Δ in protein
– change in protein  change in structure and/or function
Restriction Enzymes:
• Discovered in bacteria
• Cut DNA at specific locations
T A
T A
T A
C G
C C
T A
G C
A T
T A
C G
G C
Genetic Expression: from DNA to cell function/structure
DNA  mRNA  Proteins  cell function/structure
This is the big picture:
The instructions on DNA
make proteins when the
cell receives a signal and
then those proteins are
synthesized and used as
enzymes, transport
proteins, receptors,
hormones or as building
materials for the cell so
that the cell can carry out
its functions
•structure
•transport
•contraction
•receptors
•cell ID
•hormones/signaling
Protein Synthesis and the Genetic
Code
DNA template strand
3-43