Chapter 11 and Chapter 12 Overview

Chapter 11:

Mendelian Genetics: Studied traits of pea plants from generation to generation. A good study because it is readily available, controlled, matting, and visible)

Alleles: Version of a gene and it’s found on homologous chromosomes

ex: 🟥🟧🟨

Recessive VS Dominant Alleles

a: ‘‘Covered up’’ A: ‘‘Are expressed’’

Heterozygotes VS Homozygotes

two different alleles Aa two same alleles AA or aa

Phenotype VS Genotype

physical appearances; 🟥 genetic make-up Ex; AA or Aa

Mendel’s Law of Genetics:

  1. Law of segregation: during gamete formation, two alleles separate into different gametes.

  2. Law of independent assortments: alleles on different chromosomes segregate independently of each other.

Non-Mendelian Genetic: Multiple alleles or Many versions of a trait (proteins)

ex: Blood Typing: Proteins on outside of blood cells.

Incomplete (CO) dominance:

Incomplete: Heterozygote is in the middle

Co-dominances: two separate distinguishable traits.

Epistasis: a gene in one location controls the expression of the gene

Polygenic Inheritance: Physical appearance controlled by two or more alleles(additive effect)

ex: human skin color

Environmental factor: Various environmental factors such as chemicals, toxins, temperate, light pH, ect

ex: hydrangea color changes with soil pH

Sex-Link Traits:

Traits present on the sex chromosomes (X or Y).

Females: Need 2 copies of a recessive allele to express the trait.

Males: Need only 1 copy of a recessive allele (X-linked traits mostly show in males) (e.g., colorblindness).

Pedigrees: A family tree that traces traits over many generations.

  • Males: ▢

  • Females: ◯

  • Shaded means has the trait: ⬤ 🔳

  • Half-shaded means it is a carrier: ◨ ◑

  • Line means mating ◯— ▢

Chapter 12: Transcription and Translation (protein production)

Transcription: The production of RNA from DNA templates

  • Initiation: Small proteins bind to the promoter and recruit RNA polymerase to the gene.

  • Elongation: RNA polymerase matches RNA nucleotides to DNA in the same order.

  • Termination: RNA polymerase reaches a stop signal on the DNA.

    mRNA Processing: Only in eukaryotes, mRNA is processed before it leaves the nucleus.

  • Processing of Introns and Exons (Splicing):

  • Introns: Areas of RNA that are removed.

  • Exons: Areas of mRNA that get expressed.

Translation: The synthesis of proteins using RNA instructions; the production of a polypeptide from an RNA template

  • Initiation: The small subunit of the ribosome recognizes and binds to the mRNA.

  • Elongation: The amino acid chain grows as tRNA recognizes codons on mRNA to deliver the correct amino acid.

  • Termination: A tRNA reads the “stop” codon, and translation ends.

Codons:

  • A 3-letter “word” on mRNA.

  • tRNA has a matching anti-codon.

  • 1 codon = 1 specific amino acid.

  • 64 possible codons for 20 amino acids mean multiple codons for the same amino acid.

Types of RNA:

  1. mRNA (Messenger RNA):

    • Carries genetic information from DNA to the ribosome.

    • Contains codons that specify the amino acid sequence of the protein.

  2. tRNA (Transfer RNA):

    • Brings amino acids to the ribosome during translation.

    • Contains an anti-codon that matches the codon on the mRNA.

  3. rRNA (Ribosomal RNA):

    • Forms the core of the ribosome and catalyzes protein synthesis.

    • Helps ensure the proper alignment of mRNA and tRNA

Additional Information:

Genetic Code:

Universal: The genetic code is nearly universal, shared by almost all organisms.

Redundant: Multiple codons can code for the same amino acid.

Unambiguous: Each codon specifies only one amino acid.

Ribosome Structure:

Large Subunit: Contains the peptidyl transferase center, which forms peptide bonds.

Small Subunit: Binds to the mRNA and ensures correct base-pairing between the codon and anti-codon.

Post-Translational Modifications:

Phosphorylation: Addition of phosphate groups to proteins.

Glycosylation: Addition of sugar molecules to proteins.

Proteolysis: Cleavage of proteins into smaller fragments.