Genetics Definitions Flashcards
chromosomes
threads made up of 40% DNA and 60% protein
found in the nucleus
carry genetic info in the form of genes
gene
a section of DNA that codes for the production of a protein
unit of inheritance
located on DNA of a chromosome
homologous pair
two chromosomes of equal length with the same sequence of genes
heredity
the passing on of features from parents to offspring by means of genes
gene expression
the way in which genetic information is decoded from a gene and used to make a protein
DNA
deoxyribonucleic acid
a nucleic acid that carries and passes on genetic info in the nucleus of a cell
RNA
ribonucleic acid
a nucleic acid that carries info of an amino acid sequence from the genes to ribosomes in the cytoplasm and uses this info to form functioning proteins
non coding dna
does not code for a protein
genetic code
sequences of bases in DNA that code for the production of a specific protein
triplet/codon
sequence of three bases that code for an amino acid
anticodon
sequence of three bases on tRNA that are complementary to the sequences of three bases on mRNA
transcription
copying a sequence of bases from DNA to mRNA with the aid of RNA polymerase in the nucleus of the cell
translation
synthesis of proteins by forming chains of amino acids in the ribosome with the help of mRNA, rRNA and tRNA
DNA profile
making and examining a pattern of bands from the DNA of one person which can be compared with the DNA profile of another person
genetic screening
testing for the presence of a specific or altered gene
species
a group of similar organisms capable of interbreeding with each other and producing fertile offspring
variation
differences between members of the same species
causes : mutation, sexual reproduction
acquired variation
not inherited
learned or developed in life
eg playing a musical instrument
inherited variation
controlled by genes
eg blood type
mutation
a spontaneous change in the amount or structure of DNA
mutagen
agents that cause mutation
eg X Rays, gamma radiation, cigarette smoke
chromosome mutation
change in structure or number of chromosomes
eg downs syndrome
gene mutation
a change in a single gene
eg cystic fibrosis
evolution
inheritable change within a population in response to a change in the environment over time, giving rise to a new species
natural selection
members of a species with genetic traits that allow them to be better adapted to survive in their environment, will reproduce and pass these on to following generations
speciation
the production of a new species as a result of evolution
genetic engineering
artificial manipulation of genes
gamete
sex cell capable of fusion
fertilisation
the fusion of the egg and sperm nuclei to form a diploid zygote
somatic cell
all other body cells that are not sex cells (diploid)
allele
different forms of the same gene
locus
position of a gene on a chromosome
homozygous
two alleles for a trait are the same
pure breeding
homozygous
hybrid
heterozygous
dominant
where one alleles effect masks the effect of another
recessive
an alleles effect is only expressed when in the homozygous condition
genotype
genetic makeup
phenotype
physical make up
incomplete dominance
neither allele masks the effect of another
linkage
genes for different traits are located on the same chromosome
gives rise to less variation
sex linkage
a characteristic controlled by a gene on a sex chromosome
eg colour blindness
pedigree study
a diagram showing the genetic history of a group of related organisms
monohybrid cross
study of one characteristic
dihybrid cross
study of two characteristics
non nuclear inheritance
inheritance of DNA through mitochondria or chloroplasts
from mother
genetics
the study of how traits are passed from parent to offspring
