1. Genome Organization. Flashcards
What is a genome?
It is the genetic material of an organism.
What are the two types of genomes present in eukaryotes?
Nuclear and mitochondrial genomes.
Each cell contains ….. nuclear genomes and how many copies, where is it located?
Has 1 nuclear genomes, 2 copies and its located in the nucleus.
T or F?
Each cell contains 2-10 copies of mt- DNA?
False.
Each cell contains 1000 - 10,000 copies of mt- DNA, whereas EACH mitochondria countains 2 -10 copies .
What are the characteristics of nuclear genome?
Location: Nucleus.
DNA copies: 2 copies of 23 chromosomes.
Genome structure: Linear
Genome size: 3.2x10^6 Base pairs
Number of genes: 30,000 genes
Coding regions %: 2% coding / 98% non- coding.
Mode of inheritance: from both mother and father ( diploid )
What are the characteristics of mitochondrial genome?
Location: Mitochondria
Copies: Each mitochondria has SEVERAL copies.
Genome structure: Circular ( E. coli )
Genome size: 16,569 base pairs.
Number of genes: 37 genes.
Coding region: 97% coding 3% non coding
Mode of inheritance: from mother only ( haploid )
Important facts about genomes!
- It is the total DNA content in a cell.
- It contains all DNA including the protein coding DNA.
- An organism has only 1 genome
- The study of it is called genomics
Important facts about genes!
- It is only a segment of the DNA molecule
- It contains only protein coding DNA.
- thousands of genes in an organism .
- The study of it is called genetics.
What is the structure of dna?
Double helical.
A nucleotide is made up of?
A phosphate group, sugar, and a base.
Two nucleotides are linked together by what bonds and where?
By equal covalent bonds. Located between a sugar of one nucleotide and a phosphate group of another.
What bonds link the 2 strands of dna together?
H bonds.
Complementary base pairing occurs between 2 strands .
A-T / C-G
Explain why the two strands of the dna are anti parallel?
5 to 3 on one strand and 3 to 5 on the other.
How are such large dna fibers compactly packaged in a small nucleus?
Because of histone proteins. (H2A, H2B, H3, H4)
These histone proteins form an Octomer and wraps the dna strand TWICE.
Each complex of histone proteins and dna wrapping around them are called
Each complex of histone proteins and dna wrapping around them are called ?
Nucleosomes
Nucleosomes are separated by a…..?
30 -bp linker dna.
What histone protein binds on the linker site and protects the nucleosomes from becoming a mess / tangled.
All the nucleosomes are further condensed into a loop like structure, this loop further coils and gets denser to form a sister chromatid as seen in METAPHASE.
What happens in mitotic cell division?
Linear DNA packing with histone proteins and forming supercoiled sister chromatid occurs in metaphase stage .
What chromosomes are used in karyotyping? And why?
- metaphase chromosomes and it is for identifying the chromosomes number and structure abnormalities.
Example of these abnormalities are: - XO & XXY
- translocation.
What happens when a doubled stranded dna is heated?
The h bonds start breaking
Breaking a double stranded dna into single strands is known as?
DNA denaturation.
What is renaturation?
When a denatured DNA in solution is cooled down, complementary single strands DNA can reform into a double stranded DNA with hydrogen bonding in the presence of water.
