inheritance 2022 Flashcards
genome
Entire DNA of an organism
Gene
Section or Molecule of DNA that codes for a specific protein
DNA molecule structure
Double helix formed of 2 strands linked by a series of paired bases: Adenine (A) with Thymine (T) and Cytosine (C) with Guanine(G)
RNA molecule structure
Single strand, contains Uracil (U) instead of Thymine (T)
First stage of of protein synthesis
Transcription
Transcription
1. The 2 DNA strands are separated and the nucleotide bases of the template strand are exposed
2. Free RNA nucleotides form complementary pairs with exposed DNA bases
a. Remember DNA has Uracil (U) not Thymine (T)
3. The adjacent RNA nucleotides are joined via bonds to form an mRNA molecule
4. When a gene has been transcribed, the mRNA molecule leaves the DNA and passes out of a nuclear pore to a ribosome in the cytoplasm
5. The 2 DNA strands re-join
Translation
- The mRNA molecule enters the ribosome
- At the ribosome, each mRNA codon is matched with a complementary anticodon on a tRNA molecule
- The ribosome catalyses the formation of a (peptide) bond between the amino acids, gradually forming a (polypeptide/amino acid) chain
- The amino acid/polypeptide chain is folded to form a functional protein
- The process continues until a stop codon is reached on the mRNA
chromosome
carries genetic information as DNA
Allele
a different form/version of the same gene
Dominant allele
represented by an upper-case letter (e.g. D); only 1 dominant allele is needed in the genotype for it to be expressed in the phenotype.
Recessive Allele
represented by a lower-case letter (e.g. d); 2 copies of the recessive allele are needed in the genotype to for it to be expressed in the phenotype.
Genotype
the genetic makeup of an individual regarding a particular feature; the alleles each cell has for a particular gene.
E.g. DD, Dd or dd.
Phenotype
the physical manifestation of a genotype.
E.g. dimples or no dimples.
Homozygous
an individual with 2 identical alleles for a particular gene, e.g. BB or dd.
Heterozygous
an individual with different alleles for a particular gene, e.g. Bb.
Codominance
When both allelles are expressed in the phenotype