DNA, Genes, Chromosomes Flashcards
What is a “gene?”
- A base sequence (ie. section of DNA) that will code for the amino acid sequence of a polypeptide and code for a functional RNA.
Give two examples of functional RNA.
- tRNA
- Ribososomal RNA.
What is meant by term “locus?”
- FIXED position of particular gene on DNA molecule (known as locus.)
True or False
The hair colour gene will have a different locus for each human.
- False.
- Hair colour gene will always have the same locus (ie. same location on DNA molecule) in all humans.
- BUT… the versions of the gene may be different (ie. different alleles.)
What is an “allele?”
- An allele is one of a number of alternative forms of a gene (ie. two genes that code for SAME TYPE OF CHARACTERISTIC -e.g., hair colour - but different alleles = brown/ black.)
() - extra info for claririfcation.
What is a chrosome? Where are they found in eukayrotic cells? How many pairs of chromosomes do humans have in somatic cells?
- Compact DNA associated with histones forms a chromosome.
- Found in nucleus (in eukaryotic cells.)
- Pairs of chromosomes: 23 pairs (46 in total.)
What is a “homologous pair” of chromosomes?
- Homologous pair of chromosomes are exactly the same size, have exactly the same genes but may have different alleles.
How many homologous pairs of chromosomes does a human have?
- 23 homologous pairs of chromosomes.
What is DNA like in euakryotic cells?
- DNA is linear in shape.
- DNA is tightly-coiled to fit in nucleus (as chromosomes), tightly-wound around proteins; called histones –> forming chromosomes.
- DNA = very long
- Found in nucleus.
What is DNA like in prokaryotic cells?
- DNA is short
- DNA is circular
- DNA is not associated with proteins.
- DNA found free-floating in the cytoplasm.
True or False
The DNA of mitochondria/ chlorplasts are like the DNA of eukaryotic cells - as these structures are found in eukaryotic cells.
- FALSE!!
- DNA contained in mitochondria/ chloroplasts = short, circular, not associated with histones/ proteins.
What is the name of the protein that DNA winds around in eukaryotic cells to form chromosomes?
- Histones
True or False
The locus of a particular gene can change.
- False.
- Locus is FIXED position of the gene.