2. Single stranded
Ribose Sugar
Phosphate group
Base: Adenine, Uracil, Cytosine, Guanine
Structure of RNA
3. Three Types of RNA
Messenger RNA (mRNA) – transfers DNA
code to ribosomes for translation.
Transfer RNA (tRNA) – brings amino
acids to ribosomes for protein synthesis.
Ribosomal RNA (rRNA) – Ribosomes are
made of rRNA and protein.
4. Transcription
RNA molecules are produced by copying
part of the nucleotide sequence of DNA
into complementary sequence in RNA, a
process called transcription.
During transcription, RNA polymerase
binds to DNA and separates the DNA
strands.
RNA polymerase then uses one strand of
DNA as a template from which
nucleotides are assembled into a strand of
mRNA.
8. Translation
During translation, the cell uses
information from messenger RNA to
produce proteins.
1.Transcription occurs in nucleus.
2.mRNA moves to the cytoplasm then to the
ribosomes. tRNA “read” the mRNA and
obtain the amino acid coded for.
3.Ribosomes attach amino acids together
using a peptide bond, forming a
polypeptide chain.
4.Polypeptide chain keeps growing until a
stop codon is reached, creating a protein.
10. Mutations
Mutations are changes in the DNA code.
Gene mutations result from changes in a
single gene.
Chromosomal mutations involve changes
whole chromosomes.
12. Gene Mutation
Point Mutation – Affect one nucleotide
thus occurring at a single point on the
gene. Usually one nucleotide is
substituted for another nucleotide.
13. Gene Mutation
Frameshift Mutation – Inserting an extra
nucleotide or deleting a nucleotide
causes the entire code to “shift”.
16. Gene Regulation
All (with a few exceptions) of an organism’s
cells have the same DNA. Why then are
there different cells?
The gene expression is different. In other
words, cells ‘differentiate’ by expression of
some genes and suppression of others.
Cells respond to their environment by
producing different types and amounts of
protein. Can you think of a situation where
this might happen?
17. Gene Regulation: Producing
Proteins
Injury repair: cells can adapt to
environmental changes such as an injury
which requires repair by activating new
genes
Cancer is a disease of uncontrolled and
invasive cell reproduction. Cancers result
when the genes responsible for coding the
proteins that regulate cell division mutate
and divide rapidly.
19. Questions
Which base in RNA is replaced by uracil?
How many mRNA codons are illustrated on
the previous slide?
What is the name of the enzyme that
creates the mRNA copy from DNA?
What is the name of the sugar in the
mRNA nucleotides?
What is the mRNA transcript for the DNA
sequence, TTACGC
21. Questions
What structure assists tRNA in translating
the mRNA in the cytoplasm?
The role of tRNA is to carry a(n):
22.
23. Gene Regulation
In simple cells (prokaryotic) lac genes
which are controlled by stimuli, turn genes
on and off.
In complex cells (eukaryotic) this process
is not as simple. Promoter sequences
regulate gene operation.
24. How Does it Work?
RNA Polymerase looks for a region on the
DNA known as a promoter, where it binds
and begins transcription.
RNA strands are then edited. Some parts
are removed (introns) - which are not
expressed – and other that are left are
called exons or expressed genes.
25. Chromosomal Mutations
Deletion – Part of a chromosome is
deleted
Duplication – part of a chromosome is
duplicated
Inversion – chromosome twists and
inverts the code.
Translocation – Genetic information is
traded between nonhomologous
chromosomes.
Synthesis: to build
Transcription: produces an RNA copy of DNA
Translation: tRNA supplies appropriate amino acid
RNA = Ribonucleic Acid
The different types of cells in a multicellular organism result from 'cellular differentiation', which can be defined as “the divergence in structure and function of different types of cells as they become specialized during an organism’s development”.
