W14 L1 - BIOS3240 Genetics and Evolution - Human Genome

Flashcards covering key concepts about the genome, its evolution, and content.

Genome

The DNA sequence of an organism that encodes the information that underpins and directs most of the biological processes taking place within that organism.

Human Genome Size

3.2 billion bases of DNA, which if printed would fill a stack of paperback books 200 feet high or extend 3,000 km.

C-value

The 'constant' value of haploid DNA content per nucleus, measured in picograms.

Base pairs (bp)

The number of base pairs in a DNA sequence, often measured in kilobases (kb), megabases (Mb), or gigabases (Gb).

C-value paradox

There is no clear correlation between organismal complexity and genome size.

Chromosome Number vs. Complexity

There is no direct relationship between the number of chromosomes and the complexity of a species.

Gene Content in Prokaryotes

Linear relationship between genome size and number of genes in Prokaryotes.

Gene Content in Eukaryotes

No linear relation between genome size and number of genes in Eukaryotes.

Junk DNA

DNA that doesn’t have a known function or code for a gene.

What Constitutes the Non-Coding Part of the Genome?

Exons, repetitive sequences, and regulatory sequences.

Two Main Categories of Repetitive DNA

Tandem Repeats and Interspersed Repeats.

Tandem Repeats

Simple DNA sequences repeated consecutively.

Types of Tandem Repeats

Microsatellites (2-10 bp), Minisatellites (10-60 bp), and Satellite repeats (>60 bp).

Interspersed Repeats

Complex DNA sequences repeated in different locations in the genome.

Types of Interspersed Repeats

Segmental Duplications/Copy Number Variants and Transposable Elements.

Segmental Duplications / Copy Number Variants (CNVs)

Long DNA sequences (>1kb) with nearly identical sequences (90-100%) found in multiple locations due to duplication events.

Transposable Elements or Jumping Genes

Genes that can 'jump' to different locations in the genome.

Classes of Transposable Elements

Transposons (DNA intermediate) and Retrotransposons (RNA intermediate).

Mechanisms of Genome Evolution

Duplication of entire chromosome sets (polyploidy), alterations of chromosome structure, duplication and divergence of gene-sized regions of DNA, rearrangements of parts of genes, and single nucleotide mutations.

Polyploidy

Having more than two sets of homologous chromosomes; common in plants but usually fatal in humans.

Types of Chromosome Rearrangements

Fission, fusion, translocation, and inversion.

Gene Duplications

Wrong pairing of homologues during meiosis.

Post-Duplication Scenarios

Loss of duplicated copy, preservation of two copies, subfunctionalization, neofunctionalization.

Rearrangements of Parts of Genes

Exon shuffling and exon duplication.