Class 4 - 20/06/24:

• Viruses: intracellular parasite

• Virus structure: made up of a capsid(coat) with a nucleic acid genome inside(Can’t have both DNA and RNA)

• Basic Steps: attachment(adsorption) - specific attachment but not infected yet; and injection - penetration - from bacterium to host

• Lytic Cycle: transcribe and translate viral genome; replicate; lysis of host

  • Early genes - hydrolase and capsid

  • Hydrolase: destroy host cell genome

    • Replicate genome

    • Lysis of host and release of viral particles

• Lysogenic Cycle: integrate viral genome into host then induce with normal host activity and excision and lytic cycle happens

  • Transduction - insertion of new DNA that was not present before

• Productive Cycle: does not destroy the host cell

• RNA Viral Genomes: can be both positive and negative types of RNA viruses

  • (+) RNA requires translation of RNA to protein - RNA dependant and RNA polymerases make the proteins

  • (-) RNA need a copy of RNA pol., and translate the now + RNA to proteins that negative

• Prions - do not follow central dogma because they are self-replicating proteins

  • No DNA/RNA

  • no membranes

  • no organelles

  • very small

  • extremely stable

• Prion categories = normal and mutagenic - mutant can lead to cell death

  • Mutant = Bad prions - come from a mutation in a prion, can be inherited, or by ingesting a bad prion → bad ones can make good ones bad too

• Viroids: circular RNA, no capsid, must be co-infected, no protein code - block translation

  • two different mechanisms make viroids -

    • one by taking negative RNA, translating it to positive RNA to form many +RNA to form viroid copies

    • One by taking -RNA and wrap +RNA to form a viroid copy

• Bacteria:

  • Can have three different shapes:

    • Round = coccus

    • Rod = bacilli

    • Spiral = spirillum

    • can have a flagella to move it or cilia

    • Bacteria have a cell wall and a cell membrane

  • gram + = stain dark and have a cell membrane covered by a cell membrane - easier to get in

  • gram - = stain light and have an inner membrane covered by a cell wall covered by an outer cell membrane - harder to get in

  • Temperature-dependent bacteria:

    • mesophiles → 30*C

    • Thermophiles → 100*C

    • psychrophiles → 0*C

  • Oxygen use Bacteria:

    • Obligate aerobe = use it and need it

    • Facultative anaerobe = can use it and survives

    • Tolerant anaerobe = doesn’t need it but can tolerate

    • Obligate anaerobe = can’t use it and can die due to O2

  • Energy/Nutrients of Bacteria

    • Photoauto = uses light and makes it on its own

    • Chemoauto = use chemicals by self

    • Photohetero = carnivorous plants

    • Chemohetero = need other energy sources

• Reproduction - use of binary fission to duplicate identical copies

• Binary Fission - growth follows an exponential growth pattern

• Conjugation(genetic Diversity) - helps to provide genetic diversity, rather than increase population size

  • horizontal gene transfer - donor-to-recipient transfer with direct contact

  • F- is the donor(male) and F+ is the female recipient - gives an F plasmid, not a genome

Class 5 - 27/06/24:

• Cell Biology and organelles

Class 6 - 01/07/24:

• Meiosis - making of 4 cells that differ from the parent cell and each other

  • Non-disjunction - failure to separate DNA during meiosis

• Genetics - study of genes

  • Allele - the genes found on a chromosome

  • Trait - the characteristic that appears from the alleles

    • Polymorphic - several types of one trait

    • polygenic - several genes that determine a trait

• Classical Dominance: homozygous dominant/recessive, heterozygous

  • Genotype: combination of alleles

  • Phenotype: physical characteristics

• Incomplete: display a blend of the parental phenotypes

  • ex. red flower RR x white flower WW = pink flower RW

• Co-dominance: both alleles are expressed independently and at the same time

  • Ex. Blood types → I^A I^B i

• Epistasis: dominance between two different genes - one gene can mask or modify the expression of another gene ex. Albinism

• Test-cross: where one of an unknown genotype is crossed with another of a homozygous recessive genotype

• Backcross - F1 x P

• Mendel’s Laws

  • Law of segregation - alleles separate during gamete formation

  • Law of independent assortment - one allele is independent of another allele

• Single-gene crosses - 4 types

  • Homozygote 1 x Homozygote 1

  • Homozygous dominant x homozygous recessive

  • heterozygote x homozygote dom/rec

  • heterozygoye x heterozygote

• Rules of Probability

  • A AND B - multiply the probabilities

  • A OR B - add individual probabilities

• Linked Genes: genes found close together on the chromosome

  • Dihybrid crosses = crosses between two traits

    • F1xF1 = 9:3:3:1 → unlinked

    • F1xHomozygous recessive Parent = 1:1:1:1 → unlinked

      • When the actual ratio differs from this, they will be linked genes as they don’t follow the expected ratios

• Recombination: genes that do not assort independently

  • recombination frequency = # recombinants/total offspring x 100

    • Tells us the map units(mu) distance between genes on the chromosome

      • 1 mu = 1 cM(Centimorgan)

• Hardy Weinberg: tells us that allele frequencies within a population do not change from generation to generation

  • p + q = 1 → allele frequency where p = dominant allele and q = recessive allele

  • pp + 2pg + qq = 1 → genotype frequency where 2pq is the heterozygous allele

• 5 Conditions where Hardy-Weinberg hold true:

  • No mutation

  • No natural selection

  • No migration

  • Total random mating

  • Large population size