Unit 4 - Genetic information, variation and relationships between organisms Flashcards
Gene mutation
a change to one or more nucleotide bases in DNA that could result in a change in genotype which may be inherited
Autosome
a chromosome which is not a sex chromosome
Homologous chromosomes
a pair of chromosomes, one maternal and one paternal, they have the same gene loci so determine the same features but they are not necessarily identical as they have different alleles. they are capable of pairing during meiosis
Codon
a sequence of three adjacent nucleotides in mRNA that codes for one amino acid
Anticodon
a sequence of three adjacent nucleotides on tRNA that is complementary to a particular codon on a mRNA molecule
Chromosome
a thread like structure made of protein and DNA by which hereditary information is physically passed from one generation to the next
Allele
different forms of a gene with different base sequences and different codes
Diploid
cell or nucleus containing pairs of homologous chromosomes
Haploid
cell or nucleus containing single, unpaired chromosomes
Nucleotides
complex chemicals made of an organic, nitrogenous base, a sugar and a phosphate. They are the basic units of which DNA and RNA are made
DNA helicase
enzyme that acts on a specific region on the DNA molecule to break the hydrogen bonds between the bases causing the two strands to separate and expose the nucleotide bases
RNA polymerase
enzyme that joins together nucleotides to form messenger RNA during transcription
Transcription
formation of mRNA molecules from the DNA that makes up a particular gene. first stage of protein synthesis
Polymerases
group of enzymes that catalyse the formation of polymers from monomers
ATP
nucleotide found in all living organisms, which is produced during respiration and is important in the transfer of energy
Chromatid
one of the two strands of a chromosomes that are joined together by a single centromere prior to cell division
Exons
portions of DNA within a gene that codes for proteins. they are joined together during splicing
Introns
portions of DNA within a gene that do not code for a polypeptide. they are removed from the pre-mRNA after transcription in splicing
Histones
proteins, which together with DNA, make up the chromosomes of eukaryotic cells
Gamete
reproductive (sex) cell that fuses with another gamete during fertilisation
Gene
section of DNA on a chromosome that controls a feature by coding for formation of one or more specific polypeptides or functional RNA
Translation
the latter part of protein synthesis when the mRNA is used as a template to which complementary tRNA molecules attach and the amino acids link to form a polypeptide
Chromatin
the material that makes up chromosomes. it consists of DNA and the histone proteins
Splicing
the process by which base sequences corresponding to the introns are removed and the functional exons are joined together
DNA replication
the process in which the double helix of a DNA molecule unwinds and each strand acts as a template on which a new strand is constructed
Crossing over
the process where a chromatid breaks during meiosis and rejoins to the chromatids of its homologous chromosome so that their alleles are exchanged
Locus
the specific linear position of a particular gene on a certain chromosome
Human genome
the complete set of genes in a cell, including those in mitochondria and/or chloroplasts