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Chapter 11.2 Notes
Protein Synthesis and Gene Expression
BAT list questions to be
answered today:
I. Who is involved in the process?
A. Two different nucleic acids
1. __DNA______
How are DNA and RNA similar and
different?
2. ___RNA_____
What are the complementary bases
for RNA?
B. __Ribosome____ - site of protein synthesis
C. Make a Venn Diagram to compare DNA to RNA
DNA
BOTH
DNA: Deoxyribonucleic
Acid
Strands: 2
Sugar: Deoxyribose
4 bases:
Adenine, Thymine,
Guanine, Cytosine
Where in cell?
Stays in nucleus
Nucleic
Acids
A, G, C
Store
genetic
info
Where in the cell can you find
RNA?
RNA
Where does protein synthesis occur?
How many different amino acids are
there?
RNA: Ribonucleic Acid
What does the sequence of amino
acids determine?
Strands: 1
What is the importance of
transcription and translation?
Sugar: Ribose
Where in the cell do transcription
and translation take place?
4 bases:
Adenine, Uracil,
Guanine, Cytosine
***Uracil replaces
thymine in RNA
Where in cell?
Nucleus & cytoplasm
II. Three types of RNA and their functions
1. mRNA: messenger RNA
What are the functions of mRNA
and tRNA?
What is the monomer of a protein?
****************************
Why does a cell need
proteins to function
properly?
Enzymes for chemical
reactions; hormones for
chemical messengers; etc
What sugar is found in
DNA? RNA?
Deoxyribose and Ribose
2. tRNA: transfer RNA
3. rRNA: ribosomal RNA
What base is used in RNA,
but not DNA? What is its
complementary base pair?
Uracil (U); Adenine
A-U
III. Summary of Protein Synthesis
DNA  mRNA  tRNA  protein
1. The process of going from DNA to mRNA is called_transcription.___
Who Am I?
DNA
2. The process of going from mRNA to a protein is called_translation.____
transcription
mmRNA
N
A
tRNA
Amino acid
translation
IV. Transcription
a. The process of going from DNA to __mRNA.___
b. The steps of transcription
1.
First DNA unzips itself along the segment of code needed for a
certain protein.
2.
mRNA is made by forming __complementary bases_____
on the unzipped portion of DNA.
3.
DNA’s code is copied into groups of 3 bases at a time called
__codon__.
4.
Each codon codes for ___1___amino acid.
5.
Once the mRNA strand is transcribed, it can now leave the nucleus to
find a __ribosome__ to carry out the next step.
IV. Translation
a. The process of taking mRNA to a ribosome and synthesizing a protein
b. Ribosomes can not understand the code from mRNA, so a translator is
needed
c. This is where tRNA comes in. tRNA reads the mRNA codons, and brings back
the appropriate amino acid
1. tRNA is clover leaf shaped.
2. On one end, it carries the __amino acid__ (like a tow truck.)
3. At the other end, it has a three letter triplet code called an
__anticodon__.
4. Anti-codons are complementary to the mRNA codons.
d. Amino Acids and Codons
1. There are __20__amino acids.
2. A codon is a sequence of ___3___nitrogen bases.
3. We can determine what amino acid is being coded for by using a
___codon chart___.
4. This is what is known as the __genetic code____.
e. Reading a Codon Chart
1. Some amino acids can have more than one __codon___.
2. There are three STOP codons, __UAA, UAG, & UGA____.
3. There is __1__ start codon, ___AUG____.
f. How a translator works
1.
tRNA anticodons meet up with mRNA__start codon__AUG.
2.
The next tRNA anticodon meets up with the corresponding mRNA.
3.
Each tRNA molecule brings in an __amino acid__.
g. Protein synthesis continues until a __stop codon__ is reached.
V. Regulation of Transcription and Translation
Why can’t DNA leave the
nucleus?
Too big & stay protected
What nucleic acid CAN
leave the nucleus?
RNA
List the RNA base pair
rules.
A-U
G-C
Write the complementary
mRNA strand for the DNA
below.
DNA
ATC CGG TTA ATG
UAC GCC AAU UAC
mRNA
Below are some mRNA
codons, find the tRNA
anticodon
AUG
UAC
Methionine
CCA
GGU
Proline
GCU
CGA
Alanine
GUA
CAU
Valine
In order to read the codon
chart, what form must the
genetic code be in?
Codon on mRNA
a. Gene expression is a __regulated process where genes can be turned on __
__off as needed to environmental factors___________________________.
How does the ribosome
know when to stop?
Reaches a stop codon