8.1 Protein Synthesis and Expression: Translation

porcupineideaBiotechnology

Dec 16, 2012 (4 years and 6 months ago)

96 views

Copyright © 2010 Pearson Education, Inc.

8.1 Protein Synthesis and Expression: From
gene to protein


Protein synthesis



the process of using
instructions carried on a
gene

to create
proteins.


Several steps are involved and require
both
DNA

and
RNA
.


Gene


a sequence of DNA that encodes a
protein


Protein



a large molecule composed of
amino acids

Copyright © 2010 Pearson Education, Inc.

Copyright © 2010 Pearson Education, Inc.

8.1 Protein Synthesis and Expression: From
Gene to Protein


DNA


Double
-
stranded


Each
nucleotide

composed of deoxyribose,
phosphate, and nitrogenous base


4 bases: adenine, thymine, guanine,
cytosine

Copyright © 2010 Pearson Education, Inc.

8.1 Protein Synthesis and Expression: From
Gene to Protein


DNA

(a) DNA

DNA nucleotide

Phosphate

group

Thymine (T)

Deoxyribose

Copyright © 2010 Pearson Education, Inc.

8.1 Protein Synthesis and Expression: From
Gene to Protein


RNA


Single
-
stranded


Nucleotides comprised of
ribose
,
phosphate, and nitrogenous base


4 bases: A,
C,
G, and
Uracil

Copyright © 2010 Pearson Education, Inc.

8.1 Protein Synthesis and Expression: From
Gene to Protein


RNA

(b) RNA

RNA nucleotide

Phosphate

group

Uracil (U)

Ribose

Copyright © 2010 Pearson Education, Inc.

8.1 Protein Synthesis and Expression: From
Gene to Protein


The flow of genetic information in a cell is
DNA



RNA


protein

Polymer of nucleotides

(two complementary

strands)

Polymer of nucleotides

(single strand)

Polymer of amino acids

DNA

RNA

Protein

Transcription

Translation

ala

ser

val

his

Copyright © 2010 Pearson Education, Inc.

8.1 Protein Synthesis and Expression: From
Gene to Protein


There are 2 steps in going from gene to
protein


Transcription

(DNA


RNA)





Translation

(RNA


Protein)

Copyright © 2010 Pearson Education, Inc.

8.1 Protein Synthesis and Expression:
Transcription


Transcription occurs in the nucleus.


RNA polymerase

binds to the
promoter

region of the gene.


RNA polymerase

zips down the length of
gene, matching RNA nucleotides with
complementary DNA nucleotides

Copyright © 2010 Pearson Education, Inc.

8.1 Protein Synthesis and Expression:
Transcription

DNA

mRNA

RNA polymerase

Promoters have distinct

nucleotide sequences that

RNA polymerase recognizes.

RNA nucleotides

Promoter

Copyright © 2010 Pearson Education, Inc.

8.1 Protein Synthesis and Expression:
Transcription


The product of
transcription

is
messenger RNA (
mRNA
).


Transcription Video

Copyright © 2010 Pearson Education, Inc.

8.1 Protein Synthesis and Expression:
Translation


Translation occurs in the cytoplasm
(outside the nucleus).


Translation requires: mRNA (made during
transcription), amino acids, energy (ATP),
and some helper molecules.


Ribosomes


Transfer RNA (tRNA)

Copyright © 2010 Pearson Education, Inc.

8.1 Protein Synthesis and Expression:
Translation


Ribosomes


The ribosome is
composed of rRNA
and comprises a
small and a large
subunit.

Large

subunit

Small

subunit

Copyright © 2010 Pearson Education, Inc.

8.1 Protein Synthesis and Expression:
Translation


Transfer RNA:
tRNA carries amino
acids and matches
its

anticodon
with

codons
on mRNA

Anticodon

mRNA

tRNA

Amino

acid

Binding site for

amino acid

Region of internal

complementarity

Codon

Copyright © 2010 Pearson Education, Inc.

8.1 Protein Synthesis and Expression:
Translation


A protein is put together one amino acid at
a time.


The ribosome attaches to the mRNA at the
promoter region.


Ribosome facilitates the docking of
tRNA

anticodons

to mRNA
codons
.


When two
tRNAs

are adjacent, a bond is
formed between their amino acids
.


Translation Video

Copyright © 2010 Pearson Education, Inc.

8.3 Genetically Modified Foods


All agricultural
products are the result
of genetic modification
through selective
breeding. Artificial
selection does not
move genes from one
organism to another,
but does drastically
change the
characteristics of a
population.

Copyright © 2010 Pearson Education, Inc.

8.3 Genetically Modified Foods: Why
Genetically Modify Crop Plants?


Increase shelf life,
yield, or nutritional
value


Golden rice has
been genetically
engineered to
produce beta
-
carotene, which
increases the rice’s
nutritional yield.

Copyright © 2010 Pearson Education, Inc.

8.3 Genetically Modified Foods: Modifying
Plants with the Ti Plasmid and Gene Gun


Transgenic organism



the result of the
incorporation of a gene from one organism
to the genome of another. Also referred to
as a
Genetically Modified Organism
(GMO).

Copyright © 2010 Pearson Education, Inc.

8.3 Genetically Modified Foods: Effect of GM
Crops and the Environment


Benefits: Crops can be engineered for
resistance to pests, thus farmers can
spray fewer chemicals.


Concerns: Pests can become resistant to
chemicals. GM crops may actually lead to
increased use of pesticides and
herbicides. GM crop plants may transfer
genes to wild relatives.

Copyright © 2010 Pearson Education, Inc.

8.4 Genetically Modified Humans: Stem Cells


Stem cells



undifferentiated
cells, capable of
growing in to many
different kinds of
cells and tissues.

Copyright © 2010 Pearson Education, Inc.

8.4 Genetically Modified Humans: Stem Cells


Stems cells might be used to treat
degenerative diseases such as
Alzheimer’s or Parkinson’s, multiple
sclerosis, or liver, lung, or heart disease.


Stem cells could also be used to grow
specific tissues to treat burns, heart attack
damage, or replacement cartilage in joints.

Copyright © 2010 Pearson Education, Inc.

8.4 Genetically Modified Humans: Human
Genome Project


Human Genome Project



international
effort to map the sequence of the entire
human genome (~20,000


25,000 genes).


For comparative purposes, genomes of other
model organisms (
E. coli
, yeast, fruit flies,
mice) were also mapped.


It was sequenced using the technique of
chromosome walking.

Copyright © 2010 Pearson Education, Inc.

8.4 Genetically Modified Humans: Human
Genome Project

Sequence from Lab 1

Compiled sequence

Sequence from Lab 2

Sequence from Lab 4

Sequence from Lab 3

Copyright © 2010 Pearson Education, Inc.

8.4 Genetically Modified Humans: Cloning
Humans


Genetic engineering is controversial.