Biology Notes

Genetics

If you want to know the gametes that can be produced by an individual with genotype AaBb, you use the FOIL method so the answer AB, Ab, aB, ab

The reason for doing a test cross is to identify heterozygous individuals with the dominant phenotype.

Genes are found on chromosomes not in the cytoplasm. If you want to determine the phenotype of an organism, you must look at the physical characteristics of the organisms.

If an offspring is said to be homozygous recessive it’s genotype could be TTss or ttSS

A pedigree is chart that traces the inheritance of a trait in a family.

A test cross is when you cross a true-breeding recessive trait with an unknown gentype that shoes the dominant phenotype.

Amoeba Sisters Videos

DNA replicates so the new cell can also get a copy of the DNA

Key enzymes in this process are:

  • Helicase: Goes through hydrogen bonds and breaks them open

  • DNA Polymerase: Builds new DNA strand by replicating molecules of DNA

  • Primase: Primer made of RNA that goes on

  • Ligase: Glues DNA fragments together

Lagging strand is the DNA strand that is synthesized during replication. It’s discontinuous and just a fragment.

A codon chart has 64 combinations showed and the are 20 different types of amino acids.

Nucleic Acids

Messenger RNA (mRNA) leaves the nucleus to take messages to ribosome to make proteins.

Ribosomal RNA (rRNA) catalyzes formation between amino acids and peptide bonds.

Transfer RNA (tRNA) transfers amino acids to area of protein synthesis

DNA is a molecule in every organism that carries genetic info

Transcription

Comes before translation. In the nucleus, it’s the process of copying DNA’s instructions to make mRNA.

Translation

Happens in cytoplasm, then ribosomes. tRNA transfers amino acid to complementary bases on mRNA. The ribosomes then make protein. DNA is not directly involved.

Law of Dominance: Dominant genes always mask recessive genes

Law of Segregation: During meiosis, alleles for a trait separate. Each gamete gets 1 allele for each trait.

Law of Independent Assortment: Each trait is inherited separately and each homologous pair separates alone from all other pairs.