DNA , Genes and Chromosomes Flashcards
Structure of DNA in eukaryotic cells
- Contain linear DNA molecules that exist as chromosome
- Chromosomes are found in the nucleus
Properties of Eukaryotic DNA
- Really long - has to be wound up to fit in the nucleus
- Wound around proteins called histones - help support DNA
- Coiled up really tightly to make a compact chromosome
What are examples of eukaryotic cells?
- Animal
- Plant
Why is mitochondria and chloroplasts own DNA similar to prokaryotic DNA?
- Circular and shorter than DNA molecules in the nucleus
- It is not associated with histone proteins
What do prokaryotic’s DNA carry as?
Chromosomes
Properties with prokaryotic DNA
- DNA molecules are shorter and circular
- DNA isn’t wound around histones - condense to fit in cell by supercoiling
What is a gene?
Sequence of DNA bases that code for either a polypeptide or functional RNA
What does sequence of amino acid in polypeptide form?
A primary structure
What do different polypeptides have?
Different number and order of amino acids
What does the order of base in gene determine?
The order of amino acids in a particular polypeptide
What is a triplet?
Each amino acid is coded for by a sequence of three bases in a gene
How to make a polypeptide?
DNA is first copied into messenger RNA (mRNA)
first stage of protein synthesis
What happens to genes that do not code for a polypeptide?
Code for functional RNA
What is functional RNA?
RNA molecule other than mRNA
performs special tasks during protein synthesis e.g tRNA and rRNA -form part of the ribosomes
What is a cell’s GENOME?
Complete set of genes in the cell
What is a cell’s PROTEOME?
Full range of proteins that the cell is able to produce
What are introns?
In eukaryotic DNA , genes that do code for polypeptide contain sections that don’t code for amino acids
What are extrons?
Genes that do code for amino acids
What are removed during protein synthesis?
Introns - don’t effect the amino acid order
What does prokaryotic DNA not have?
Introns
What are non-coding repeats/
DNA sequence that repeats over
Areas don’t code for amino acids
What are alleles?
Different forms of the same gene - code slightly different verisons of same polypeptide
Where can alleles coding for the same characteristics will be found at what?
Fixed position (locus) on each chromosome in a homologous pair
