Unit C2/C3 Mendelian/Molecular Genetics Flashcards
What is the difference between X-linked and autosomal traits
sex-linked traits are dependent on the sex chromosomes whereas autosomal traits are not
What are the definitions of the following: Gene, Allele, Trait, Heterozygous, Homozygous, Dominant and Recessive
Gene: Molecular unit of heredity; it is what is passed down from one generation to the next
Allele: One or more alternate forms of genes
Trait:
Heterozygous: A genotype that contains two different alleles (ex; AA
Homozygous: A genotype that contains two of the same allele (ex: aa)
Dominant: A trait that is always expressed when the associated allele is present; represented by a capital letter
Recessive: A trait that is only expressed when the genotype is homozygous; represented by a lowercase allele
What is DNA replication
DNA replication is the process in which an original strand of nucleotides acts as a template strand for forming a new strand. this is known as semi-conservative replication
What are the steps of DNA replication
- The double helix relaxes and untwists using gyrase
- The hydrogen bonds between the nitrogen bases are broken using helicase, then the strands separate to become templates
- Free-floating nucleotides are lined up with the nitrogen bases in the template strands. Primase enzyme tells DNA polymerase where to build
- The free-floating nucleotides are glued into place using ligase
- the replicated strands are checked for errors using proofreading enzyme, any unresolved errors result in mutations
- two double stranded molecules of DNA now exist; each strand is half new and half og
What are the processes of protein synthesis
- Transcription (in the necleus)
- Translation (happens on ribosomes in the cytoplasm)
What are the steps of transcription
- DNA double helix untwists & separates using helicase to break the hydrogen bonds
- mRNA begins forming a complementary strand to one side of the DNA template using uracil(U) instead of Thymine(T)
- mRNA leaves the nucleus & goes into the cytoplasm
- mRNA carries instructions for protein synthesis for protein production to the ribosomes
What are the steps of translation
- Ribosomes attach to mRNA & expose one codon (3 bases) at a time
- mRNA codon directs the amino acid that should be placed within the protein sequence
- the amino acid attaches in place using its TRNA anticodon which is complementary to the mRNA strand
- a peptide bond forms between each amino acid, eventually the ribosome comes across a stop codon and detaches the protein.
What are the different types of mutations
Silent, missense, nonsense, frameshift, translocation, inversion.
What are the different categories of mutations
Point mutations: (Gene mutation) changes a single base pair of DNA sequence. May or may not change the sequence of amino acids.
Chromosomal mutations: alterations that affect the whole genes rather than individual nucleotides
What is a silent mutation
A mutation that dose not result in a change in the amino acid sequence
What is a missense mutation
A mutation that results in the single substation of one amino acids
What is a nonsense mutation
A mutation that converts a codon for an amino acid into a stop codon
What is a frameshift mutation
a mutation that causes the reading frame of the codon to change(adding/deleting bases)
What is a translocation mutation
The transfer of a fragment of the DNA from one gean in the genome to another location
what is an inversion mutation
The reversal of a segment of DNA with in a chromosome e
What is the difference between a genotype and a phenotype?
A genotype is the alleles with in the gene, a phenotype is the trait that is expressed by the gene
Who was Gregor Mandel? What did he do?
Gregor Mendel was an Austrian monk who is considered the “Father” of genetics for his contributions to field. He made his discoveries by experimenting on a common pea plant, from theses experiments he developed four principles called “Mendel’s laws of heredity”
What are Mendel’s Laws of Heredity
Some of the founding principles of genetics were based on Gregor Mendel’s experiments on pea plants. These laws are known as the law of unit characteristics, The law of dominance, The law of segregation, and The law of independent assortment
What is the law of unit characteristics?
The first law. “Traits are controlled by genes which occur in pairs (one copy from each parent)”
What is the law of Dominance
Second law. “The dominant form of a trait prevents prevents the expression of the recessive form”