Lecture 1

Chromosome Disorder

Caused by excess or deficiency of all/part of a chromosome; accounts for ~50% of spontaneous abortions and occurs in 7 in 100 live births.

Single-gene disorder

A disorder caused by a mutation in one or both copies of a single gene, affecting approximately 2% of the population.

Multifactorial disorder with complex inheritance

Disorders resulting from the combined effect of multiple genetic defects, often influenced by environmental factors, affecting more than 50% of the population.

6.6 billion

How many base pairs are in a diploid cell?

45,000

How many genes are in the human genome?

20,000

How many protein coding genes are there?

25,000

How many noncoding RNA genes are there?

Single-copy sequence

Unique sequence of DNA that includes most genes and regulatory elements; less than 15% of the genome encodes proteins.

Satellite DNA

Tandem repeats of relatively short (5-170 bp) sequences, clustered in specific regions of the genome (centromeres, heterochromatin), and comprising 10-15% of the genome.

Dispersed repeats

Repetitive elements dispersed throughout the genome, including short- and long- interspersed nuclear elements (SINEs and LINEs), comprising approximately 30% of the genome, important for their role as transposons that can lead to mutations.

16,600

How many base pairs in mitochondrial DNA?

38

How many genes in mitochondrial DNA?

14

How many protein coding genes in mitochondrial DNA?