Topic 1: DNA, Genes, The Continuity of Life
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define organelle
a membrane bound compartment in a cell that performs a specialised function
name the general features of prokaryotes
• lack distinct nucleus • no membrane-enclosed organelles • contain free floating ribosomes
name the general features of eukaryotes
-distinct nucleus - contain membrane-bound organelles - contain ribosomes
describe DNA in prokaryotes
a single circular chromosomes and plasmids
define intron
a segment of DNA or RNA molecule that doesn’t code for proteins and interrupts the sequence of genes
where is DNA found in prokaryotes
found in the nucleoid region
where is DNA found in eukaryotes
found in the nucleus
define mitochondria
organelle in both eukaryotic cells (heterotrophs and autotrophs), site of cellular respiration
explain mitochondrial DNA (mDNA)
a double stranded, circular molecule with no introns
recall the basic structure of DNA
• carried hereditary info • a double helix structure with two complementary strands • nucleotides are the building blocks of DNA/RNA
what are nucleotides
a group of molecules that, when linked together, form the building blocks of DNA/RNA
what are nucleotides made of
a deoxyribose sugar, a phosphate group, a nitrogenous base
what are the 4 dif types of nitrogenous bases in nucleotides
Adenine and Thymine Guanine and Cytosine (Thymine is only found in DNA, in RNA it is replaced by Uricil)
whats the dif between maternal and paternal
maternal - from mother paternal - from father
define diploid
cell containing 2 complete sets of chromosomes - one from each parent
define haploid
cell having a single set of unpaired chromosomes, usually a gamete (sex cell)
what are homologous chromosomes
• have one paternal and one maternal, containing the same genes (the sex genes)
define autosomal chromosomes
chroms. not related to gender/ sex (chromosomes 1 to 22)
what are the differences between make and female when it comes to chromosomes 23
• females have two homologous pairs of X chromosomes • males have one X and a shorter Y chromosomes
what is a human karyotype
an individual’s complete set of chromosomes
define gene
segment of DNA that codes for a specific phenotypic trait
define allele
the different variations of a gene
define gene locus
a fixed positions on a chromosomes where a specific gene is found (location)
homozygous?
same alleles (AA)