Human genome

ORGANIZATION OF HUMAN GENOME

CONTENT-

GENOME. FLOW CHART OF HUMAN GENOME. NUCLEAR GENOME. MITOCHONDRIAL GENOME. REPETITIVE DNA.

What is Genome ? A genome is an

organism's complete set of DNA, including all of its genes.

Each genome contains all of the information needed to build and maintain that organism.

 The genome includes both the genes and the non-coding sequences of the DNA/RNA.

“Genome is thus the entire collection of genes and all other functional and non functional DNA sequences in an organism in a haploid set of chromosomes”.

Structural genes- DNA segments that code for some specific RNAs or proteins. Encode for mRNAs, tRNAs , snRNAs, scRNAs.

Functional sequences- Regulatory sequences- occur as regulatory elements (initiation sites, promoter sites , operator sites , etc.)

Nonfunctional sequences- Introns and repetitive sequences. Needed for coding, regulation and replication of DNA. Much more in no than functional sequences.

DIFFRENCE :-NUCLEAR DNA MITOCHONDRIAL DNA Found inside the

nucleus. 75% Nuclear DNA. Less Mutation. Linear shape. Few copies of nuclear

DNA in nucleus of cell.

Found inside mitochondria

25% Mitochondrial DNA.

20 times more mutation .

Circular shape. 1000 of

mitochondrial copies in mitochondria.

NUCLEAR GENOME Nuclear DNA, is DNA contained within

a nucleus of eukaryotic organisms. Nuclear DNA encodes for the majority of the genome in eukaryotes, with DNA located in mitochondria and plastids .

Nuclear DNA adheres to Mendelian inheritance, with information coming from two parents, one male and one female, rather than matrilineally, as in mitochondrial DNA.

MITOCHONDRIAL GENOME: MITOCHONDRIAL GENOME At just 16,569 bp Contains just 37 genes. 13 of these genes code for proteins

involved in the respiratory complex The other 24 specify non-coding RNA

molecules that are required for expression of the mitochondrial genome.

 REPETITIVE DNA The proportion of repetitive DNA is calculated by

using length of repetitive DNA divide by genome size. There are two categories of repetitive DNA in genome:

1.  tandem repeats and 2. interspersed repeats.

1.Tandem repeats:  Are usually caused by slippage

during replication, unequal crossing-over and gene conversion, satellite DNA and microsatellites are forms of tandem repeats in the genome.

2. Interspersed repeats:  Mainly come from transposable

elements (TEs), but they also include some protein coding gene families and pseudogene.

SATELLITE DNA: Found in Eukaryotes. Satellite DNA consists of very large arrays

of tandemly repeating, non-coding DNA . Satellite DNA is the main component of

functional centromeres , and form the main structural constituent of heterochromatin]

MINISATELLITE DNA: A minisatellite is a tract of repetitive DNA in which

certain DNA motifs (ranging in length from 10–60 base pairs) are typically repeated 5-50 times. 

Minisatellites occur at more than 1,000 locations in the human genome and they are notable for their high mutation rate and high diversity in the population.

Minisatellites are prominent in the centromeres and telomeres of chromosomes, the latter protecting the chromosomes from damage.

MICROSATELLITE DNA: A microsatellite is a tract of repetitive DNA in

which certain DNA motifs (ranging in length from 2–5 base pairs) are repeated, typically 10-100 times.

 Microsatellites occur at thousands of locations in the human genome and they are notable for their high mutation rate and high diversity in the population.

TRANSPOSABLE ELEMENTS: A transposable element (TE or transposon) is

a DNA sequence that can change its position within a genome, sometimes creating or reversing mutations and altering the cell's genome size.

Transposition often results in duplication of the TE. Barbara McClintock's discovery of these jumping genes earned her a Nobel Prize in 1983.

LINEs  Long Interspersed Nuclear Elements (LINE)

are a group of genetic elements that are found in large numbers in eukaryotic genomes, comprising 17% of the human genome (99.9% of which is no longer capable of retrotransposition, (is considered "dead" or inactive)).

Among the LINE, there are several subgroups, such as L1, L2 and L3.

Retrotransposons: can be transcribed into RNA, which are then duplicated at another site into the genome . Retrotransposons can be divided into Long terminal repeats (LTRs) and Non-Long Terminal Repeats (Non-LTR).

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