topic 4 - genetics

• genome

  • all the genetic material of an organism
  • a lot contained in the nucleus but not all
• allele

  • a different version of a gene
  • a different genetic variant of a trait, often with a observable phenotype
  • you can have different versions of a gene (eg. different versions of hair pigment genes - ie. phenotype) but all hair pigment genes are the same
  • it's the same gene, just diffa erent allele. ie. blonde hair allele, brown hair allele
• homologous pairs

  • a group of chromosomes that share the same genes, in the same order, BUT may have different alleles (ie. may not be genetically identical)
  • eg. one gene on one chromosome may be the dominant allele, and the other chromosome at the same gene spot will have a different allele.

  A) homologous pair

  
• what is a gene

  • a segment of DNA that encodes one or more traits (usually protein)
• DNA

  • a set of instructions to encode a protein
  • fundamentally useless
• the central dogma

  A) transcription

  B) translation

  C) mRNA

  D) DNA

  E) protein

  
• transcription

  • DNA to mRNA
  • occurs in the nucleus (most eukaryotes)
  • occurs in the cytoplasm (prokaryotes)
• translation

  • mRNA to protein
  • occurs in the ribosomes
  • not all ribosomes are at the rough ER, some can occur in the cytoplasm
• transcription process

  1. enzymes use one of the strands of DNA within a gene as a template to produce mRNA
  2. RNA polymerase (enzyme) and transcription factors binds to the promoter (a specific part within the gene) and separates 2 strands apart.
  3. RNA polymerase moves down the template strand, producing mRNA as well as zipping the DNA back up.
  4. mRNA will exit the nucleus where all the genetic material is (chromatin) and move to the cytoplasm and find a ribosome
• translation process

  1. the mRNA acts as a code for a SPECIFIC protein. each set of 3 bases on this mRNA is called a codon.
  2. each codon will code for a specific anticodon, which will be carried by a specific tRNA
  3. each tRNA is linked to an amino acid, this sequence is called a reading frame
  4. since their are 4 bases (A,U,G,C) and each codon has 3 letters, there are 64 possible codons which is more than enough the amino acids we need.
  5. https://www.youtube.com/watch?v=bKIpDtJdK8Q
• difference between DNA replication and DNA transcription

  • replication is copying the DNA using one strand as a template using DNA polymerase and its purpose is to make new cells
  • transcription is transferring the genetic information in DNA to mRNA using RNA polymerase and its purpose is to make proteins
• types of cellular division

  • Binary fission
  • mitosis
  • meiosis
• Binary fission

  • cellular division process for prokaryotes
  • a single cell duplicates its DNA and splits into 2 identical daughter cells

  A) cytoplasm

  B) daughter cells

  
• chromatids

  • strands of replicated chromosomes

  A) 92

  
• interphase

  • undergone by both meiosis and mitosis
  • consists of cell growth, DNA replication and daily cell functions
• meiosis vs mitosis

  
• diploid vs haploid

  A) one

  B) haploid

  C) diploid

  D) two

  E) homologous

  F) non homologous