1. Big Idea 3 - Genetics and Information
09 Mutation and genetic variation
Lesson 1: Changes in genotype can result in changes in phenotype.
Lesson 2: Biological systems have multiple processes that increase genetic variation..
Lesson 3: Viral replication results in genetic variation; infection can introduce genetic variation into the hosts

2. Genotype changes can result in phenotypic changes
Alterations in a DNA sequence can lead to changes in the type or amount of the protein produced
Can affect phenotype
Can be positive, negative, or neutral
Depending on:
Effect on resulting mRNA sequence
Effect on resulting polypeptide / protein

3. Mutations in DNA Mutations are random changes in the DNA sequence
Factors:
Errors in DNA replication
Errors in DNA repair mechanisms
External factors
ionizing radiation (X-rays, UV)
reactive chemicals (Nitrous acid)
HNO2 - substitutes bases for other bases and compounds

4. Mutations in DNA (cont.)
Mutations are the primary source of genetic variation.
Whether or not a mutation is detrimental, beneficial or neutral depends on the environmental context
HNO2 - substitutes bases for other bases and compounds

5. Errors in mitosis or meiosis can result in changes in phenotype
Changes in chromosome number often result in new phenotypes
triploidy often causes sterility
increased vigor of other polyploids
ex. increase of chlorophyll and starch production

6. Errors in mitosis or meiosis can result in changes in phenotype (cont
For humans, changes in chromosome number often result developmental limitations
Trisomy 21 - Down syndrome
XO - Turner syndrome

7. Changes in genotype
May affect phenotypes that are subject to natural selection.
Can enhance survival:
Pesticide resistance
Sickle cell and heterozygote advantage
As you know:
Selection results in evolutionary change

9. Big Idea 3 - Genetics and Information
09 Mutation and genetic variation
Lesson 1: Changes in genotype can result in changes in phenotype.
Lesson 2: Biological systems have multiple processes that increase genetic variation..
Lesson 3: Viral replication results in genetic variation; infection can introduce genetic variation into the hosts

10. Viral replication
How does it differ from other reproductive strategies?
Viruses don’t have cells
Use only genetic information
DNA
mRNA
RNA + reverse transcriptase

11. Viral structure nucleic acid protein coat
Some kind polymerase to copy the nucleic acid
a lipid envelope (for some)

13. Viral cycle of infection
Infection → Replication → Self-Assembly → Release

14. Viral Infection Types Lytic
Virus injects cell with RNA and RNA polymerase
Viral DNA is transcribed into mRNA
Cell ribosomes make viral protein components which self-assemble
Cell explodes (lyses) with viruses

16. Viral Infection Types Lysogenic
Virus injects cell with RNA and reverse transcriptase
Viral DNA is incorporated into the cell’s genome
Cell RNA polymerase makes viral protein components which are exported out of the cell like any other protein
Host cell continues this way indefinitely; host can remain asymptomatic

17. Viruses Evolve Rapidly
Viral polymerases make many more mistakes than cellular polymerases.
Additionally, co- infection of a cell by 2 viral strains leads to viral recombination

18. Ex. HIV HIV is a retrovirus that infects helper-T immune cells.
The viral genome is reverse transcribed into DNA and integrated into the host cell’s genome.
The eventual immune system collapse causes AIDS, unless the infection is halted.

19. Viruses transmit DNA or RNA when they infect a host cell
Transduction
Viruses spreading from one bacteria to another
Some viruses will end up with bacterial DNA, instead of viral DNA