Definitions Flashcards
Def of Chromatin fibres
structures that are found in the nucleus in which genetic material in the form of DNA molecule is organised.
Gene
a small segment of DNA in chromosome where its specific of nucleotides code for a polypeptide with a specific sequence of amino acids.
Also regarded as a unit of inheritance
Nucleic acids
- form genetic material of all living organisms and essential for life
- macromolecules made up of nucleotides
DNA (deoxyribonucleic acid)
double stranded mol. that consists of two polynucleotide chains wound around each other to form a double helix
Transcription
process by which a gene is copied to form a piece of messenger RNA (mRNA)
Translation
process by which genetic information on the mRNA is read by a ribosome to synthesise a polypeptide
Genetic code
desc. the relationship between the sequence of DNA bases in a gene and the corresponding protein sequence that it encloses.
Genetic engineering
is the process of using recombinant DNA (rDNA) technology to alter the genetic makeup (genome) of an organism
Transgenetic organisms
organisms that possess a gene or genes that have been transferred from a
different species
turgidity
pressure exerted on the cellulose cell wall due to the large volume of the vacuole
endocytosis
exocytosis
ingestion
process in which food is taken into the body
chemical digestion
the HYDROLYSIS of large insoluble food molecules into smaller soluble molecules, catalysed by enzymes
physical digestion
physical breaking up of food into smaller pieces, which increases the surface area to volume ratio of food, so that enzymes can digest the food more efficiently
absorption
process in which small and soluble molecules move from the lumen of the intestine into the bloodstream of the intestine.
assimilation
the process where absorbed food molecules are used to create new protoplasm or used to release energy (occurs in liver)
egestion
the process where undigested food (reject: wastes) known as faeces is removed from the body
physical digestion in mouth
gene locus
specific location/position of gene along the length of a chromosome
Linkage
when 2 genes located on the same chromosome, they are linked
Allele
alternative form of gene, with each allele having a slightly different nucleotide sequence
Genotype
genetic composition of ALL the ALLELES OF GENES in an organism
Phenotype
the observable physical trait of an organism
dominant (allele)
allele of gene that is expressed in the phenotype of a homozygote and heterozygote. (allele of a gene that is expressed in the phenotype under homozygous and heterozygous conditions)
recessive (allele)
allele that is expressed in the phenotype of a homozygote
homozygote
organism that has 2 of the same alleles of a gene at a particular locus on a pair of homologous chromosomes
heterozygote
organism that has 2 DIFFERENT alleles of a gene at a particular locus on a pair of homologous chromosomes
codominant
both alleles of a gene that is expressed in the phenotype of a heterozygote/ under heterozygous conditions
incomplete dominance
an allele does not show complete dominance or recessiveness over another allele.
The phenotype is INTERMEDEIATE between the phenotypes of between homozygous dominant and homozygous recessive conditions `
Mendelian Inheritance
inheritance pattern for autosomal gene pairs whereby the genetic trait displayed results from one parent’s gene over the gene inherited from the other parent
mutation
a change in the nucleotide sequence of DNA or structure of a chromosome/ no. of chromosomes of an organism
diffusion
the net movement of substances down the concentration gradient
osmosis
net movement of water molecules from a region of less negative water potential to a region of more negative water potential
