Topic 4- DNA, genes and chromosomes Flashcards
How is DNA stored in eukaryotic cells?
-Linear DNA molecules that exist as chromosomes
How is DNA arranged in eukaryotic cells?
-Thread like structures
-Each made up of one long molecule of DNA and it’s associated proteins
Where are chromosomes found?
In the nucleus
What is a DNA molecule wrapped in?
-Histone protein
What is the function of a histone proteins?
-To support the DNA
How is a chromosome formed?
-The DNA and protein is coiled up very tightly to form a compact chromosome
Which organelles have their own DNA?
-Chloroplast
-Mitochondria
Why is the DNA in chloroplast and mitochondria similar to prokaryotic DNA?
-Circular
-Shorter than DNA molecules in the nucleus
-Not associated with histone proteins
What are the main differences between prokaryotic and eukaryotic DNA
-The DNA molecules are shorter and circular
-Is not wound around histones
-Condnses by supercoiling
What is the main similarity between eukaryotic and prokaryotic DNA?
-Carry DNA as chromosomes
What is a gene?
-A sequnce of DNA bases that code for either a polypeptide or functional RNA
What does the order of the bases in a gene determine?
-The order of the amino acids in a particular polypeptide
Genes that don’t code for polypeptides code for what instead?
-Functional RNA
What is functional RNA?
-RNA molecules other than mRNA which perform special task in protein synthesis
Give an example of a functional RNA molecule
-tRNA
-rRNA
What is a proteome?
-The full range of proteins that the cell is able to produce
What is a genome?
-The complete set of genes in a cell
What are introns?
-Genes that do not code for polypeptides contain sections that do not code for amino acid
What are exons?
-Gens that do code for amino acids
What are non-coding multiple repeats?
-DNA sequences that repeat over and over again that do not code for amino acids
What is an allele?
-One of two or more versions of DNA sequence (a single base or a segment of bases)
How many pairs of chromosomes do humans have?
23 pairs (46 in total)
Why do homologous chromosomes pair up?
-They are both the same size
-Have the same genes (may have different alleles)
Where will allele coding for the same characteristic be found?
-At the same fixed position (Locus)