Gene Expression When a cell reads the DNA it doesnt directly say for example blue eyes What the DNA actually says is what types of proteins to make when to make them amp how much of them to make ID: 916521
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Slide1
Chapter 13
RNA & Protein Synthesis
Slide2Gene Expression
When a cell “reads” the DNA, it doesn’t directly say for example blue eyes.
What the DNA actually says is what types of proteins to make, when to make them, & how much of them to make.This is what we term gene expression. Expressing the genetic information by using the DNA code to create a protein that does a specific job or controls a specific trait.
Slide3Gene
Not all your DNA actually codes for something.
Some of your DNA is junk DNA.
Scientists are still not sure what all of your DNA does.However, a gene is a specific segment of DNA that does code for something. It codes for a protein!Each chromosome contains many genes controls many
proteins - traits
Slide4What is a protein?
Made up of the elements:
C, H, O, N
Chain of amino acids – polypeptideFunction as enzymes (control reactions), messengers, structural components (muscles)About 20 different amino acids (differ by their r/variable group)The particular sequence or pattern of amino acids in the chain makes one protein different from another.
Slide5Protein Structure
Slide6DNA to a protein
The sequence or pattern of these amino acids that make up a protein are coded for in your
DNA.
This is one of the ways that you DNA is the instructions that make you = you.But what happens if there is a change or mutation to the DNA?If the DNA gets change then you do not make the right protein, which means whatever job that protein was suppose to do doesn’t get done.Many genetic disorders are due to such mutations.
Slide7Overall Order
DNA
mRNA Protein
Slide8Protein Synthesis
2 stages
Transcription
Translation(nucleus) (ribosome)Convert DNA into mRNA Convert mRNA into a protein
Slide9DNA vs. RNA
DNA
Double Stranded
Does not leave the nucleusA T C GSugar - DeoxyriboseRNA
Single Stranded
Can leave the nucleus (pores)
A U C G
Sugar – Ribose
3 Types
Slide10Types of RNA
mRNA – messenger RNA
carries the message of how to make a protein from the nucleus to the ribosome determines the order of amino acids in a protein contains the codon (group of 3 “letters” on the mRNA) rRNA
– ribosomal RNA
(makes up the ribosome)
tRNA
– transfer RNA
carries or transports the amino acids needed to make the
protine
to the ribosome
contains the anticodon
Slide11Transcription
Purpose
: convert DNA into mRNA
Location: Nucleus3 Steps:InitiationElongationTerminationEnzyme: RNA Polymerase
Slide12Practicing Transcription
Let’s say this is our DNA
TACATTCGGATCWhat would our mRNA look like?Use the rules of base pairing!Except now A – U, C – G
Slide13Practicing Transcription
DNA
TACATTCGGATCmRNA AUGUAAGCCUAG
Slide14Translation
Purpose
: convert mRNA into a protein
Location: Ribosome3 Steps:InitiationBegins when the ribosome reaches the start codon (3 letters on mRNA usually AUG)
Elongation
Protein gets bigger by adding more amino acids.
Termination
Ribosome reaches a stop codon. (UAA, UAG, or UGA
)
Slide15Translation – Draw A picture!
Slide16Translation