bio chap 11 molecular genetics Flashcards
what is dna
deoxyrubonucleic acid is a molecule that carries genetic info
important for all cellular functions such as cell division and cell differentiation
cells would not be able to carry out vital functions without DNA
how is DNA organised in cells
each DNA molecule consists of 2 strands twisted around each other
a molecule of DNA is wrapped around proteins to form a single chromosome
what makes up the basic units of DNA
in a nucleotide there is
a sugar
a phosphate group
a nitrogenous base
what are the 4 nitrogenous bases
adenine <-> thymine
cytosine <-> guanine
how do nucleotides join together
nucleotides join tgt to form polynucleotidee
a sequence of nucleotides make up a gene
the sequence can vary resulting in many different genes
what is the rule of base pairing
bases if one chain are bonded to those of the opposite chain
adenine bonds with thymine via 2 hydrogen bonds
cytosine bonds to guanine via 3 hydrogen bonds
in DNA molecules, ratios of A:T and C:G are always 1:1
what is a chromosome
a tightly coiled DNA molecule consisting of many genes down its length
what are the function of proteins
responsible for determining and characteristics of an organism
what are genes
basic unit if inheritance in a living organism
sequence if nucleotides that controls the formation of a single polypeptide used to make proteins
each gene stores a message / genetic code that determines how a protein should be made in a cell
what happens when a message stored by a gene is altered
may affect body structure or function
how is a polypeptide/ protein made
the message in the gene is copied into a molecule called messenger RNA
mRNA travels from the nucleus to cytoplasm and attaches to a ribosome
the ribosome moves along mRNA synthesising a polypeptide
the polypeptide is released when the ribosome leaves the mRNA
