Download DNA, RNA, & Protein Synthesis

DNA, RNA, &
Protein Synthesis
Chapter 12
DNA-DEOXYRIBONUCLEIC ACID
STRUCTURE:
• DOUBLE HELIX (SPIRAL
LADDER)
• MADE OF NUCLEOTIDE
SUBUNITS
– PHOSPHATE
– SUGAR (DEOXYRIBOSE)
– NUCLEOTIDE BASE (A,T,C
OR G)
• THE “HANDRAILS” OF THE
LADDER ARE THE SUGAR &
PHOSPHATE
• THE “STEPS” ARE THE
BASES PAIRED UP
All of the following are subunits of a
nucleotide except which?
•
•
•
•
A.
B.
C.
D.
Phosphate
Sugar
Carbohydrate
Base
Which part of the DNA molecule
(“ladder”) contains the sugar and
phosphate?
•
•
•
•
A. the “steps” of the ladder
B. Nucleotide bases
C. Double strands
D. the “handrails” of the ladder
BASE PAIRING
• The order of
nucleotides creates a
code
– Different for every
living thing
– Even identical twins
have some differences
in their codes
BASE PAIRING
• DNA IS LIKE THE RECIPE BOOK IN
THE CELL FACTORY
– IT IS LOCATED IN THE NUCLEUS
(MAIN OFFICE) OF THE CELL.
– IT HAS SPECIFIC INSTRUCTIONS
FOR EVERY CELL IN YOUR BODY.
– ONLY THE “PAGES” OR PARTS OF
THE INSTRUCTIONS NEEDED BY A
PARTICULAR CELL ARE ACTUALLY
USED.
EX: THE DNA IN YOUR SKIN CELL
HAS ALL OF THE INSTRUCTIONS
BUT THE ONLY PART THAT IS
USED IS THE INSTRUCTIONS FOR
MAKING SKIN.
What is the role (job) of DNA?
•
•
•
•
A. making sugars
B. breaking down sugars
C. modifying proteins
D. giving directions to the cell
If a scientist compared the DNA
sequence of a human, a dog, and a
tree, she would find the two most
similar sequences would be from
the dog and the human.
• True or False?
DNA Replication
Making more DNA
• WHEN NEW CELLS OR “FACTORIES”
ARE NEEDED, THE DNA IS THE
FIRST THING TO BE COPIED. IT
OCCURS IN THE FOLLOWING STEPS:
– THE DNA LADDER “UNZIPS”
– FREE NUCLEOTIDES FLOATING IN
THE NUCLEUS PAIR UP WITH
THEIR COMPLIMENTS (A-T, C-G)
– THIS CONTINUES IN SEVERAL
POINTS ALONG THE LADDER
UNTIL THE COPYING IS
COMPLETE
What ensures that the DNA code is
copied correctly each time?
•
•
•
•
A. bases pair up A-T, C-G
B. subunits align
C. the “ladder” unzips
D. phosphates and sugars pair up
DNA Replication
Making more DNA
• THE 2 NEW LADDERS EACH CONTAIN ONE
OLD STRAND AND ONE NEW STRAND.
RNA - Ribonucleic Acid
RNA STRUCTURE:
• NUCLEOTIDE SUBUNITS
– PHOSPHATE GROUP
– SUGAR (RIBOSE)
– NUCLEOTIDE BASE
(A, U, C or G)
• SINGLE STRAND (ONE
SIDE OF A LADDER)
RNA – 3 types
FUNCTIONS:
• TO CARRY A SINGLE DIRECTION (RECIPE)
TO THE RIBOSOMES (mRNA)
• TO BRING THE AMINO ACIDS
(INGREDIENTS) TO THE RIBOSOME
ACCORDING TO THE RECIPE (tRNA)
• TO BIND THE AMINO ACIDS (INGREDIENTS)
TOGETHER TO MAKE PROTEIN-OR THE
CANDY IN OUR FACTORY. (rRNA)
RNA TRANSCRIPTION:
copying the DNA code to mRNA
• DNA “UNZIPS”- ONLY THE
PORTION NEEDED
• FREE NUCLEOTIDES PAIR
WITH THEIR
COMPLEMENTS
• ONLY A PORTION OF ONE
SIDE OF THE DNA LADDER
IS COPIED
• THE MESSENGER RNA
PEELS OFF THE DNA
TEMPLATE AND LEAVES
THE NUCLEUS TO GO TO
THE RIBOSOME
Translation:
Using mRNA to Make a Protein
• Ribosome “reads” the recipe
from the mRNA codon
• tRNA molecules bring the
amino acids in the correct order
according to the codon
– Every 3 bases codes for a
particular amino acid
– Look up the codon on page
303 of textbook to find
amino acid
• Amino acid sequence
determines the type of protein
Translation:
Using mRNA to Make a Protein
Summary:
DNA is found in nucleus
mRNA is made in the nucleus
from DNA template
mRNA carries the message to the
ribosome
Protein is made using mRNA code
like a “recipe” and amino acids
as “ingredients”
RNA can be found in 3 places.
These include all but which of the
following?
•
•
•
•
A. ribosomes
B. cytoplasm
C. nucleus
D. vacuoles
Which of the following is a
difference between DNA and RNA?
• A. DNA has deoxyribose, RNA has ribose
• B. DNA has thymine, RNA has uracil
• C. DNA is double stranded, RNA is single
stranded
• D. All of the above are differences
between DNA and RNA
Translation:
Using mRNA to Make a Protein
A sequence of DNA contains the
code:
AAT TCC TGC
What would be the amino acid
sequence?
1.transcribe:
UUA AGG ACG
2.Look up codons on table
3. Leu (leucine)
Arg (arginine)
Thr (threonine)
What is the amino acid sequence for
the DNA strand:
ATG TTA TAT GAG ?
A. TYR ASN ILE LEU
B. MET LEU TYR GLU
C. MET TYR ASN ILE STOP
D. TYR ASN LEU ILE
Mutations
• Sometimes a
mistake happens
during replication:
– The wrong base
pairs up
(substitution)
– An extra base is
inserted
(insertion)
– A base is deleted
(deletion)
Mutations
• If the mutation occurs
in a portion of DNA
that the cell needs, a
genetic defect is
caused
• If the mutation occurs
in a portion of DNA
not needed by the
particular cell, no
effect.