DNA, RNA, protein synthesis PPT notes
NUCLEIC ACIDS (What are they?):
1. One of the major organic biomolecules
2. They contain Carbon, hydrogen, nitrogen, oxygen, and phosphorus (C,H,N,O,P)
3. They store information
4. The instructions make proteins
5. Examples  DNA and RNA
What does DNA stand for? Deoxyribonucleic acid
DNA Nucleotides (monomers)
What are the three parts of a DNA nucleotide?
Sugar
N-base
Sugar
A. Phosphate group
B. 5 Carbon sugar (deoxyribose)
C. Nitrogen bases
What are the 4 nitrogenous bases of DNA:
1. Adenine
2. Guanine
Nitrogen bases
Phosphate
C
Phosphate
G
A
Label and pair
the bases in
this DNA
molecule
3. Thymine
4. Cytosine
A
T
G
Rules for Base Pairing in DNA:
AT
CG
How many strands are in a DNA molecule? Two (double helix)
What is the function of DNA?
DNA contains our genetic code which codes for proteins…the blueprint
What does RNA stand for? Ribonucleic acid
How many strands are in an RNA molecule? One – single stranded
RNA Nucleotides: parts
A. Sugar (ribose)
Nitrogen bases
B. Phosphate
C. Nitrogen base
What are the 4 nitrogenous bases of RNA:
1. Adenine
Label the RNA
molecule
2. Uracil
3. Guanine
4. Cytosine
Rules for Base Pairing with RNA:
Adenine bonds with Uracil
Guanine bonds with Cytosine
.
Sugar
Phosphate
What are the functions of RNA? It carries coded “message” of DNA and translates the “message into a protein.
What are the types of RNA? A). Messenger RNA (mRNA
B. Transfer RNA (tRNA) C) Ribosomal DNA (rRNA_
COMPARING DNA & RNA
DNA
RNA
DNA
Sugar is deoxyribose
Located in nucleus
Sugar is ribose
Located in cytoplasm
Adenine base is
present
Stores genetic information
Cytosine base is
present
Functions in protein synthesis
Guanine base is
present
Composed of nucleotides
Thymine base is
present
Template for synthesis of proteins
Uracil base is present
Transcribes the Template
Shape is double helix
More than one type
RNA
Shape is single
stranded
THE THREE TYPES OF RNA AND THEIR FUNCTIONS
Messenger RNA
ribosomal RNA
Transfer RNA
mRNA
rRNA
tRNA
“Scans and reads” the mRNA
Carries an amino acid to
ribosome to make the protein
chains
Carries DNA message to the
cytoplasm where ribosomes are
m
R
N
TWO PARTS OF
A PROTEIN SYNTHESIS
TRANSCRIPTION
DNA makes RNA
Occurs in the nucleus
Amino
acid
TRANSLATION
RNA makes Proteins
Occurs in the cytoplasm
tR
NA
to
wi
ng
STEPS IN PROTEIN SYNTHESIS
TRANSCRIPTION
TRANSLATION
Step 1: DNA unzips, exposing the free nitrogen
bases.
 Only one side (one strand)of the DNA
molecule will be used as a template.
Step 1: Occurs in the cytoplasm. mRNA meets
up and joins to a ribosome (2 subunits made from
rRNA)
Step 2: mRNA is made from the DNA template
 mRNA matches with free DNA nitrogen
bases in a complimentary fashion
 BASE PAIR RULE
(DNA) A – U (RNA)
(DNA) T – A (RNA)
(DNA) G – C (RNA)
(DNA) C – G (RNA)
Step 2: tRNA helps mRNA and rRNA in making
the protein.
Step 3: Before leaving the nucleus, mRNA will cut
out the “junk” parts of the message (the introns)
and it will keep the “non-junk” parts of the message
(the exons).
 The intron portions don’t code for anything.
Step 3:
 As ribosome moves down the mRNA, the
tRNA brings in amino acids which are
joined together by peptide bonds.
 The amino acids form a polypeptide chain
that becomes a protein.
Step 4: The exon portion of the mRNA leave the
nucleus through the nuclear pores.
 mRNA carries the DNA code in three letter
“words” called codons.
Step 4: When a stop codon is reached, the
ribosome breaks away and the polypeptide chain is
released to continue the process of becoming a
functional protein.
tRNA
 is clover-leaf shaped.
 Each one carries a specific amino acid.
 has a three letter code known as an
anticodon that complements the mRNA
codon (tells it which amino acid to bring)
Vocabulary
D
1.
Codon
a.
the complement to the codons (found on mRNA) that are
located on the tRNA
A
2.
Anticodon
b.
the building blocks of proteins
E
3.
Stop codon
c.
The set of 64 amino acids which mRNA codes for
B
4.
Amino acid
d.
a grouping of three nitrogen bases in mRNA that carry
the code for an amino acid.
C
5.
Genetic Code
e.
marks the end of a gene (the genetic code for a protein)
and protein synthesis ends.
THE GENETIC CODE