Power Point Presentation on DNA and Gene Expression.ppt

Genes are located on the chromosomes which are found in the nucleus of a cell.
When a cell is undergoing cell reproduction, the chromosomes are visible. Chromosomes appear when the chromatin condenses and become visible.
Most of the time (90%) the genetic material in the form of chromatin.
A genome is the complete genetic information contained in an individual.
(gene + chromosome)

1. DNA and Gene DNA and Gene
ExpressionExpression

2. DNADNA

Deoxyribonucleic AcidDeoxyribonucleic Acid

Double helixDouble helix

Carries genetic informationCarries genetic information

Located in the nucleusLocated in the nucleus

The monomer is a The monomer is a
nucleotidenucleotide
–A phosphateA phosphate
–A ribose sugarA ribose sugar
–A nitrogenous baseA nitrogenous base

3. What are the bases in DNAWhat are the bases in DNA

A – adenineA – adenine

T – thymineT – thymine

C – cytosineC – cytosine

G – guanineG – guanine

Base pair rulesBase pair rules

4. Where is DNA located in the Cell?Where is DNA located in the Cell?

5. Where are the genes located?Where are the genes located?

Genes are located on Genes are located on
the chromosomes.the chromosomes.

Every species has a Every species has a
different number of different number of
chromosomes.chromosomes.

There are two types There are two types
of chromosomes: of chromosomes:
autosomes and sex autosomes and sex
chromosomeschromosomes

6. Genes are located on the chromosomes Genes are located on the chromosomes
which are found in the nucleus of a cell. which are found in the nucleus of a cell.
When a cell is undergoing cell When a cell is undergoing cell
reproduction, the chromosomes are reproduction, the chromosomes are
visible. Chromosomes appear when the visible. Chromosomes appear when the
chromatin condenses and become visible.chromatin condenses and become visible.
Most of the time (90%) the genetic Most of the time (90%) the genetic
material in the form of chromatin.material in the form of chromatin.
A genome is the complete genetic A genome is the complete genetic
information contained in an individual.information contained in an individual.
–(gene + chromosome)(gene + chromosome)

7. What is gene expression?What is gene expression?
Gene expression is the Gene expression is the
activation of a gene activation of a gene
that results in a that results in a
protein.protein.

8. Gene expression takes place Gene expression takes place
differently in prokaryotes and differently in prokaryotes and
eukaryotes.eukaryotes. What is a What is a
prokaryotes? Eukaryotes? prokaryotes? Eukaryotes?

ProkaryotesProkaryotes
–No membrane bound No membrane bound
organelles (nucleus)organelles (nucleus)
–More primitive More primitive
organismsorganisms
–Only one circular Only one circular
chromosomechromosome
–Bacteria are the only Bacteria are the only
organisms that are organisms that are
prokaryotes.prokaryotes.

EukaryotesEukaryotes
–Membrane bound Membrane bound
organelles ( specialize in organelles ( specialize in
function –nucleus, function –nucleus,
mitochondria, mitochondria,
chloroplast)chloroplast)
–Chromosomes are in Chromosomes are in
pairs and not circularpairs and not circular
–All organisms that are All organisms that are
not bacteria: protist, not bacteria: protist,
fungi, plants and animalsfungi, plants and animals

9. 
In Eukaryotes, following mitosis or meiosis, In Eukaryotes, following mitosis or meiosis,
DNA recoils but certain regions remain DNA recoils but certain regions remain
relaxed for transcription. The areas of relaxed for transcription. The areas of
relaxed DNA are called relaxed DNA are called euchromatineuchromatin..

Transcription is theTranscription is the
Reading of the DNA andReading of the DNA and
Changing the code toChanging the code to
mRNA.mRNA.

Translation is changingTranslation is changing
The mRNA into a trait byThe mRNA into a trait by
Using tRNA to interpret theUsing tRNA to interpret the
mRNA.mRNA.

10. 
DNA in eukaryotes has regions of coding and DNA in eukaryotes has regions of coding and
noncoding DNA. The regions of DNA that noncoding DNA. The regions of DNA that
code for proteins or traits are called code for proteins or traits are called EXONSEXONS, ,
while the regions that do not code for while the regions that do not code for
proteins are called proteins are called INTRONS.INTRONS.
cytoplasm cytoplasm

11. 
In prokayotes, transcription and In prokayotes, transcription and
translation occur in the cytoplasm.translation occur in the cytoplasm.

In eukaryotes, transcription occurs In eukaryotes, transcription occurs
inside the nucleus in a two step inside the nucleus in a two step
sequence of events.sequence of events.
–Pre-mRNA includes both introns and exons Pre-mRNA includes both introns and exons
for the gene.for the gene.
–mRNA is only the coding portion (exons).mRNA is only the coding portion (exons).

Translation occurs in the cytoplasm at Translation occurs in the cytoplasm at
the ribosomes.the ribosomes.
–Reminder: The are three (3) types of RNAReminder: The are three (3) types of RNA
Messenager (mRNA)Messenager (mRNA)
Transfer (tRNA)Transfer (tRNA)
Ribsomal (rRNA)Ribsomal (rRNA)

12. TranslationTranslation
RNARNA
–Single strandedSingle stranded
–Does not contain thymine Does not contain thymine
but has uracil instead.but has uracil instead.
tRNA carries 3 base pair tRNA carries 3 base pair
code for specific amino code for specific amino
acid.acid.
Amino acids compose Amino acids compose
polypeptid chains.polypeptid chains.

One or more polypeptide One or more polypeptide
chains compose a proteinchains compose a protein
 proteins provide the proteins provide the
“blueprints” for our “blueprints” for our
characteristics and characteristics and
functions.functions.