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Dna Structure, Transcription and Translation

Introduction to DNA, DNA Replication, and DNA Transcription.
by

Kevin Sparaco

on 12 February 2014

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Transcript of Dna Structure, Transcription and Translation

DNA Transcription
DNA
DNA
DNA Replication
DNA structure, transcription and translation
DNA
=
D
eoxyribo
n
ucleic Acid; instructions for the organism/cell
Structure discovered by Watson, Crick, and Franklin
Made up of
nucleotides
Nucleotide:
Building block of DNA; contains a
Sugar
(Deoxyribose or ribose),
a phosphate
, and a nitrogenous
base
Follows base-pairing: A-T, C-G
Possible Bases: Adenine, Thymine, Cytosine, Guanine
Double helix
Unidirectional
When new cells are formed, they need to make sure they contain the same DNA
Replication
: Process of copying the DNA to make 2 new strands of DNA; each new strand contains half old DNA, half new DNA
Uses
enzymes
to complete the task

RNA has same structure as DNA, but the sugar is RIBOSE
Thymine is NOT present in RNA. Instead:
Uracil (A now pairs with U)
Uses RNA polymerase instead of DNA Polymerase
RNA Polymerase
: enzyme that adds nucleotides to RNA strand
Enzymes
Must physically bind to the DNA!
Helicase
: Enzyme that unzips the parent Strand of DNA
DNA Polymerase
: Enzyme that adds new nucleotides to a new strand
Warm-up
Your genome is made up
of 3
billion
nucleotides...
Practice
One side of my DNA strand reads
GTCCATGA
, what nucleotides will DNA polymerase add?
A scientist analyzed a sample of DNA and discovered it had 30% Guanine. How much Cytosine is present? How much Adenine?
What would happen to an animal cell who only had one replication forK?
DNA Transcription
DNA cannot leave the nucleus!
Nucleus
: Where DNA Instructions stored.
DNA needs to make a copy (
messenger RNA
)
DNA replication in
Prokaryotes and Eukaryotes
DNA
RNA
"Central Dogma"
- Francis Crick
DNA
RNA
Proteins
Homework: Watch until 6:20 min

watch crashcourse biology:

DNA, Hot pockets & the longest word ever
The narrator relates the central dogma to hot pockets. How? Explain what he did there.

1) what are organims made of (in general)?
2) how do you get "US" from DNA?
3) Promoter is the TATA box, What is this?
4) Is DNA copied to RNA using what enzyme? -- How is this different from the enzyme used in DNA replication?
5) What does RNA polymerase do?
6) How are DNA and RNA different?
7) what is the new copy of DNA called?
In the DNA strand above, red circles are gene and the rest?
Genes are described as
Replication happens differently in certain organism
why must eukaroytic cells have many replication forks?
Replication fork:
Starting site of DNA Replication
HOW GENES WORK:
What does it mean to transcribe?

Why must DNA be written in RNA format?
Why does DNA have to unzip?
Why is the new strand called complementary?
DNA polymerase does a proof reading of new DNA, why?
Oh! Finish DNA Paper model worksheet questions
RNA molecules that carry copies of DNA instructions are known as messenger RNA (mRNA). (short-hand copy of DNA)
mRNA
rRNA
tRNA
Messenger RNA
(mRNA)
: copy of DNA that
can leave the nucleus
and be used by the cell.
Write a summary of what happens during transcription:

use the following words:

Transcription, DNA, RNA polymerase, thymine, mRNA, nucleus, uracil, promoter, gene
What are the DNA messages that code for protein (and eventually traits)?

Does mRNA copy all the DNA?

What does the "m" stand for in mRNA?

Why is the mRNA necessary?

what does a promoter do?

If a nucleotide changes for some reason (mutation) how will that affect the translation process?
REVIEW
1) Made of accurate proportions of carbohydrate, proteins and lipids

2)DNA transcription and translation

3) TATA box is the promoter where DNA transcription begins

4) DNA to RNA needs RNA polymerase b) DNA polymerase only add DNA nucleotides (no Uracil)

5) RNA polymeraase adds new RNA nucleotides (A, U, G or C)

6) RNA has a Uracil nucleotide, is single stranded and has a Ribose sugar

7) mRNA
HW Answers
Reflect
Transfers each amino acid to ribosomes as it is specified by coded messages in the mRNA. (Carries amino acids - put em' together)
Ribosomes are proteins as well as a form of RNA known as Ribosomal RNA (rRNA). (will eventually help read mRNA)
mRNA Translation:
Identify rRNA and tRNA

Where this is taking place and why there?

Explain the role of tRNA here

How does tRNA know which amino acid to bring next?

What is a ribosome? what's it doing?

What are codon triplet's? anti-codon's?

What is the result of translation?
Sample Answer:

DNA is unzipped and read by RNA polymerase in the nucleus. RNA polymerase begins copying the nucleotides at the promoter region of the DNA to a new mRNA strand, making sure to use uracil in place of thymine. At the completion of transcription mRNA will have copied an entire gene.
Translation NOTE Questions
RNA Protein
Translation
http://www.phschool.com/webcodes10/index.cfm?fuseaction=home.gotoWebCode&wcprefix=cbp&wcsuffix=4123
Translation =
Information in mRNA is used for the assembly of a particular polypeptide sequence in cytoplasm.
AIDS
AIDS or Acquired Immune deficiency Syndrome
Uses RNA and
Reverse Transcriptase
to form DNA from RNA

The host cell uses the Viral DNA to make more virus
mRNA attaches to ribosomes (rRNA) located in cytoplasm
Step 3:
Translation in 3 Steps
Step 1:
Ribosomes (rRNA) read mRNA’s message (sets of codons)
Step 2:
**codon triplet is a set of 3 nitrogenous bases
Transfer RNA (tRNA) brings corresponding amino acids to ribosome.
Amino acids are attached in sequential order to form a polypeptide
T
universal across all life

mRNA is read 3 bases at a time called a
codon

64 possible codons (20 amino acids)

Start and Stop condons
AUG UUA AGG GGU UGA CGU AUC
Genetic Code
polypeptide sequence?
Do Now:
a) if you did not do the video HW from last week, take that out
b) Answer the following
1) What is transcription?
2) What enzyme is necessary for transcription?
3) Once you have a recipe, whats the next step?
Example 1)
DNA Sequence: ATG AAA AAC AAG GTA CAC ATC TAG
mRNA Codon: UAC UUU UUG UUC CAU GUG UAG AUC
tRNA anti-codon: AUG AAA AAC AAG GUA CAC AUC UAG
Start Your mother wear a rubber band stop
Sencence:

1) break DNA into triplet
2) Find mRNA codons
3) find tRNA anticodon
4) find sentences
5) find actual amino acids (pg 244 in text
)
1) Listen and write a brief feedback;
What did you think of Yamaguchi's story?
what did you find interesting? boring?
What new thing(s) did you learn if any? etc...

2) Google DNA mutations:Explain how mutations in the DNA sequence of a gene may or may not affect protein function.

3) Pick one of the following:

Do a quick research and find out if these have a history of mutating DNA? see what you find. Be careful of anecdotal evidence.
HOMEWORK
Steps: On a seperate piece of paper complete the following 5 steps with your DNA sequences
Cell phone signal, Wifi, microwave, x-ray, bluetooth
Mutations
Gene Mutations
Some affect a single nucleotide, others, whole chromosomes
THE CAT ATE THE RAT

THA CAT ATE THE RAT
Silent Mutation
THE CAT ATE THE RAT

THE CAT ATE THE MAT
Point Mutation
Changes in DNA
Caused by mutagens
Mutagens – Example
Ultra Violet Radiation

UV light is absorbed by DNA
Causes adjacent thymine bases to covalently bond together
Basal Cell Carcinoma
Make up your own example for a FRAMESHIFT MUTATION
i.e. THE FAT CAT SAT BAC





In your example,
Create an insertion mutation
Create a Silent mutation
Practice
Frameshift Mutation
Inserting or deleting nucleotides
Effect?
HEY MAN HOW ARE YOU BRO

HEY MAN HWA REY OUB RO_

HEY MAN HOQ WAR EYO UBR O__
Point or Frameshift? which is worse? why?
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