How Proteins Are Made
Chapter 10
10.1 From Genes to Proteins
Decoding the Information in DNA
Proteins are involved in ___________, act as ____________, and are
involved in cell membrane ______________ as well as other jobs
Proteins are coded in DNA
How do we get from DNA to protein?
Need to use ______________ to make proteins
RNA = ribonucleic acid
RNA is different from DNA in 3 ways
RNA is a _______________, DNA is a ________________
RNA has the 5-carbon sugar ___________, DNA has ______________
RNA has the nitrogen base ___________ instead of ___________ (So
in RNA A goes with U)
The DNA information is changed into RNA in a process called ___________
After Transcription 2 forms of RNA are used to change info from RNA into
amino acids which make proteins in a process called ____________________
Gene Expression (a.k.a. ______________________) is name for whole
process of proteins being made from DNA information
Transcription
DNA to RNA
Step 1: ______________________connects to part of DNA that acts as a start
signal for the gene, called a ___________
Step 2: RNA polymerase unwinds DNA exposing ______________________
Step 3: RNA polymerase then adds ______________________to exposed strand as
it moves along (A to U, G to C) and connects them with ______________________
As RNA polymerase passes, The DNA strand closes up
Only ______________________is used
RNA polymerase reaches a stop code in DNA and process stops
And now some animation!!
In Prokaryotes, transcription occurs in cytoplasm, WHY?
_______________________________________
In Eukaryotes, DNA is found in ___________ so transcription takes place
there
Many strands of RNA are made at once
Genetic Code
When a cell needs a protein it makes ___________ ___________ (mRNA)
mRNA carries info from DNA to area for translation where it can be changed
into ______________________that make-up proteins
3 nucleotide sequence = ___________
Each
codon = an ______________________, a ___________, or a
______________________
In 1961 an all uracil codon was made (UUU) and a protein made only of
______________________ was created
Other codons were deciphered
There are ____ possible codons (3 letter sequences of A, U, G, and C), and
most amino acids have more than 1 codon, this helps with mistakes
UUU and UUC are phenylalanine
UUA and UUG are leucine
RNA’s Role in Translation
Takes place in ______________________
______________________ are where protein synthesis takes place
___________ ___________ (rRNA) makes up portions of ribosome
Cells have thousands of ribosomes
___________ ___________ (tRNA) is a single strand that temporarily
carries amino acids
Have
an ______________________ that is the complement of the
codon
So
if mRNA codon says AGC, tRNA says ___________
Steps of Translation
Step 1
mRNA leaves nucleus and enters cytoplasm
mRNA, the 2 subunits of a ribosome, and tRNA with the amino acid
______________________come together
AUG is the start codon
It clicks into ___________where tRNA with methionine is brought to it
Step 2
tRNA for next codon binds into ___________carrying next amino acid
Step 3
Now both A and P site have tRNAs with amino acids
Enzymes form ______________________between amino acids
Step 4
tRNA in P-site leaves, leaving ___________behind
Step 5
tRNA in A site moves to P site
A site is now open for next tRNA
Amino acids get peptide bond again
Step 6
P site tRNA is released leaving amino acid
Steps 2-6 continue until a ___________is reached (UAG, UAA, or UGA)
which has no ___________ to match so synthesis stops
Many copies of protein are made
With a few exception (mitochondria and chloroplasts) the genetic code is the
same in all organisms
GUC is always _____________.
10.2 Gene Regulation and Structure
Protein Synthesis in Prokaryotes
Usually have 2,000 genes (humans = _________________)
Not all genes are transcribed and translated all of the time
Cells regulate (control) which genes are _________________
Escherichia coli example
You drink milk
Bacteria break down lactose and make energy or other compounds
3 _________________needed from 3 _________________
These are next to each other on gene and have same promoter site (__________)
Repressor blocks RNA polymerase from attaching and transcribing genes
When lactose is present, _________________changes shape and falls off
_________________ now can transcribe, make mRNA and eventually make
enzymes needed
Protein Synthesis in Eukaryotes
No _________________, genes are spread out
Transcription factors are proteins that help RNA polymerase get in position
Intervening DNA in Eukaryotic Genes
______________ – long segments of DNA with no coding information (debate on
what purpose they actually serve or served; may allow for new combinations)
______________ – portions of genes that are translated into proteins
After transcription, mRNA has the introns _________________
Mutations
Mutation = __________________________________
In gametes these are passed down, in body cells they are not
Gene rearrangements
Entire gene may be moved to new location
This affects function since new _________________there
May be rearranged during _________________
_________________– change in gene
Usually caused by wrong amino acid placement during protein synthesis
_________________
Single nucleotide changes
AUG AAT GCT
becomes
AUG AAT CCT and a different protein is made
_________________
Length of DNA inserted into gene
AUG AAT GCT becomes
AUG CGT TGA AAT GCT a different protein
_________________
Length of DNA removed from a gene
AUG CGT TGA AAT GCT becomes
AUG AAT GCT a different protein