Genetics Flashcards
(41 cards)
What is a gene?
A gene is the basic unit of inheritance, a discrete locus of heritable genomic sequence that affects an organism’s traits by being expressed as a functional product or by regulation of gene expression.
What is a genome?
A genome is the complete set of genes or genetic material in the cell of an organism.
How many DNA base pairs are in the human genome?
The human genome contains roughly 3.2 billion DNA base pairs.
What percentage of the human genome encodes proteins?
Only 1.5% (20,000 genes) of the genome encodes proteins.
What percentage of the human genome does not encode proteins?
98.5% of the human genome does not encode proteins.
What are the functions of encoded proteins?
Encoded proteins function as enzymes, structural components, and signaling molecules.
What is the role of proteins in the body?
Proteins are used to assemble and maintain all the cells in the body.
How are protein-coding genes arranged in higher organisms?
Protein-coding genes are separated by long stretches of DNA that do not code for any protein.
What percentage of the noncoding regions of the genome provide critical architectural planning?
80% of the noncoding regions of the genome provide critical architectural planning.
What are the major classes of functional non-protein-coding sequences found in the human genome?
- Promoter and enhancer regions provide binding sites for transcription factors.
What is the second major class of functional non-protein-coding sequences?
- Noncoding regulatory RNAs.
More than 60% of the genome is transcribed into RNAs that are never translated into protein, but regulate gene expression through a variety of mechanisms.
What is epigenetics?
Epigenetics is defined as the study of heritable chemical modification of DNA or chromatin that does not alter the DNA sequence itself.
How are different cell types distinguished?
Different cell types are distinguished by lineage-specific programs of gene expression.
What do cell type-specific differences in DNA transcription and translation depend on?
Such cell type-specific differences in DNA transcription and translation depend on epigenetic factors.
What are epigenetic factors?
Epigenetic factors are literally factors that are ‘above genetics’.
How is DNA structured in cells?
DNA in cells is not uniformly or compactly wound.
What are the two basic forms of nuclear chromatin at the light microscopic level?
- Heterochromatin: Cytochemically dense and transcriptionally inactive.
- Euchromatin: Cytochemically dispersed and transcriptionally active.
What is heterochromatin?
Cytochemically dense and transcriptionally inactive chromatin.
What is euchromatin?
Cytochemically dispersed and transcriptionally active chromatin.
What are the three broad categories of human genetic disorders?
- Chromosomal disorders
- Disorders related to mutations in single genes with large effects
- Complex multigenic disorders
What is a mutation?
A mutation is defined as a permanent change in DNA.
What happens to mutations that affect germ cells?
Mutations that affect germ cells are transmitted to the progeny and can give rise to inherited diseases.
What is the consequence of mutations that arise in somatic cells?
Mutations that arise in somatic cells can cause cancers and some congenital malformations.
What are chromosomal disorders also known as?
Chromosomal disorders are also known as cytogenic disorders.
