RNA is a single-stranded molecule that plays several roles in protein synthesis. There are three main types of RNA: messenger RNA (mRNA) which carries DNA's protein instructions to the ribosome, transfer RNA (tRNA) which brings amino acids to the ribosome during protein assembly, and ribosomal RNA (rRNA) which makes up the ribosome. RNA is produced through transcription, where RNA polymerase copies a DNA sequence into a complementary RNA strand. The RNA is then edited and moves to the ribosome for translation into a polypeptide chain. Mutations can occur through changes in single genes or whole chromosomes and can be inherited or acquired through environmental damage. While most mutations are neutral, some can cause genetic disorders

1. Don’t let this happen to
you!!

2. RNA
Ribonucleic Acid

3. Structure of RNA
 Single stranded
 Ribose Sugar
 5 carbon sugar
 Phosphate group
 Adenine, Uracil, Cytosine, Guanine

4. Types of RNA
 Three main types
 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.

5. 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.

6. 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.

7. The Genetic Code
 This is the language of mRNA.
 Based on the 4 bases of mRNA.
 “Words” are 3 RNA sequences called
codons.
 The strand aaacguucgccc would be
separated as aaa-cgu-ucg-ccc the amino
acids would then be Lysine – Arginine –
Serine - Proline

8. Genetic Codes

9. Translation
 During translation, the cell uses information
from messenger RNA to produce proteins.
 A – Transcription occurs in nucleus.
 B – mRNA moves to the cytoplasm then to the
ribosomes. tRNA “read” the mRNA and obtain
the amino acid coded for.
 C – Ribosomes attach amino acids together
forming a polypeptide chain.
 D – Polypeptide chain keeps growing until a
stop codon is reached.

10. MUTATIONS
Changes in DNA that affect genetic
information

11. Mutations
 Gene mutations result from changes in a
single gene. Chromosomal mutations
involve changes whole chromosomes.

12. Gene Mutations
 Point Mutations – changes in
one or a few nucleotides
 Substitution
 THE FAT CAT ATE THE RAT
 THE FAT HAT ATE THE RAT
 Insertion
 THE FAT CAT ATE THE RAT
 THE FAT CAT XLW ATE THE RAT
 Deletion
 THE FAT CAT ATE THE RAT
 THE FAT ATE THE RAT

13. Gene Mutations
 Frameshift Mutations – shifts
the reading frame of the
genetic message so that the
protein may not be able to
perform its function.
 Insertion
 THE FAT CAT ATE THE RAT
 THE FAT HCA TAT ETH ERA T
H
 Deletion
 THE FAT CAT ATE THE RAT
 TEF ATC ATA TET GER AT
H

14. Chromosome Mutations
 Changes in number and structure of entire
chromosomes
 Original Chromosome ABC * DEF
 Deletion AC * DEF
 Duplication ABBC * DEF
 Inversion AED * CBF
 Translocation ABC * JKL
GHI * DEF

15. Significance of
Mutations
•Most are neutral
• Eye color
• Birth marks
• Some are harmful
• Sickle Cell Anemia
• Down Syndrome
• Some are beneficial
• Sickle Cell Anemia to Malaria
• Immunity to HIV

16. What Causes
Mutations?
 There are two ways in which DNA can
become mutated:
 Mutations can be inherited.
 Parent to child
 Mutations can be acquired.
 Environmental damage
 Mistakes when DNA is copied

17. Chromosome Mutations
 Down Syndrome
 Chromosome 21 does
not separate correctly.
 They have 47
chromosomes in stead
of 46.
 Children with Down
Syndrome develop
slower, may have heart
and stomach illnesses
and vary greatly in their
degree of inteligence.

18. Chromosome Mutations
 Cri-du-chat
 Deletion of material on 5th
chromosome
 Characterized by the cat-like
cry made by cri-du-chat
babies
 Varied levels of metal
handicaps

19. Sex Chromosome
Abnormalities
 Klinefelter’s
Syndrome
 XXY, XXYY, XXXY
 Male
 Sterility
 Small testicles
 Breast enlargement

20. Sex Chromosome
Abnormalities
 XYY Syndrome
 Normal male traits
 Often tall and thin
 Associated with antisocial and behavioral
problems

21. Sex Chromosome
Mutations
 Turner’s Syndrome
 X
 Female
 sex organs don't
mature at
adolescence
 sterility
 short stature

22. Sex Chromosome
Mutations
 XXX
 Trisomy X
 Female
 Little or no visible differences
 tall stature
 learning disabilities
 limited fertility

25. Some mutations even
make it on SNL!