1. Introduction Flashcards
Length og DNA
2m/nucleus
Difference between human and chimpanzee genomes
Only 4%
Homolog
DNA sequence from common ancestral gene
Ortholog
Genes in different species that evolved from a common ancestral gene by speciation. Normally, orthologs retain the same function in the course of evolution
Paralog
Generated by duplication within the same genome, may gain new functions
How similar is the genome of two individuals?
99.5% identity
Definition of CpG islands
- Regions of DNA of at least 200 bp in length
- G+C content >50%
- A ratio of observed vs. expected CpGs close to or >0.6
- (Cytosine, phosphodiester bond, guanine)
CpG islands found in or near approximately 40% of….. of mammalian genes
Promoters
Amount of DNA in somatic cells differ based on..?
- Presence and number of nuclei
- Different stages of cell cycle
Is the DNA sequence identical in all somatic cells?
No, in T cells and B cells it is different (somatic gene rearrangement)
DNA encodes for
- RNA and proteins
- Lipids and carbohydrates are non-templated
Genome
The complete genetic material of the cell
Genetics
Science focusing on individual genes, the inheritance and variability
Genomics
Science focusing on the entire genome and the interaction of genes
Epigenetics
Science focusing on inherited, however not DNA sequence encoded changes of gene expression
(The study of changes in organisms caused by modification of gene expression rather than alteration of the genetic code itself)
The active strand that participates in transcription of mRNA
Antisense or non-coding strand. Transcribes the sense mRNA
The nucleosome consist of
8 histone molecules + 146 nucleotide pairs of DNA
Gene
The unit of inheritance, part of DNA or RNA
Locus
Location of a given gene on a chromosome
Allele
Gene variant at a given locus
Wild type allele
The most frequent variant of a given gene in nature
Genotype
Genetic composition characteristic for an individual or a locus
Phenotype
Measurable and observable features of a cell or an individual
Homozygote
Identical alleles at the same loci of the chromosome pair
Heterozygote
Different alleles at the same loci of the chromosome pair
Hemizygote
Carries only a single copy of the gene
Dominant allele
A gene variant that phenotypically always results in a given characteristic (even in heterozygotes)
Recessive allele
A gene variant that manifests phenotypically in a homo- and hemizygotes only
Ploidy
Refers to the number of homologues chromosomes of a cell
Haploid
A cell containing a single set of chromosomes
Diploid
A cell containing two sets of chromosomes
Mendels laws
- Law of uniformity
- Law of segregation
- Law of independent assortment
Law of uniformity
All F1 generation plants produce e.g. yellow-round seeds
Law of segregation
The two alleles for each gene separate during gamete formation
Law of independent assortment
Alleles of genes on nonhomologous chromosomes assort independently during gamete formation
Nuclear DNA is inherited from … while mitochondrial DNA is inherited from …
All ancestors, a single lineage (mother)
Repetitive sequences in the human genome (4)
- Long interspersed elements (LINE) (autonomous)
- Short interspersed elements (SINE) (non-autonomous)
- Retrovirus-like elements (LTR transposons)
- DNA transposons
SNV (Single nucleotide variant)
A variation in a single nucleotide without any limitations of frequency.
1 DNA molecule is built up of..
2 polynucleotide chains
How many base pairs is there in a human somatic cell?
2x 3x10^9 (diploid)
Interphase consists of.. and DNA is in what form?
G1, S, G2. DNA: chromatin
What happens in M phase
Cell division, DNA in chromosome form
1 sister chromatid is how many DNA molecules?
1 DNA molecule
The genetic code (6 features)
- Consists of triplets
- Degenerated (redundant)
- Comma-free, non-overlapping
- Almost completely unicersal
- Wobble effect
- Unambiguous