1. Genome Organization.

Question 1

What is a genome?

Answer 1

It is the genetic material of an organism.

Question 2

What are the two types of genomes present in eukaryotes?

Answer 2

Nuclear and mitochondrial genomes.

Question 3

Each cell contains ….. nuclear genomes and how many copies, where is it located?

Answer 3

Has 1 nuclear genomes, 2 copies and its located in the nucleus.

Question 4

T or F?

Each cell contains 2-10 copies of mt- DNA?

Answer 4

False.

Each cell contains 1000 - 10,000 copies of mt- DNA, whereas EACH mitochondria countains 2 -10 copies .

Question 5

What are the characteristics of nuclear genome?

Answer 5

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 )

Question 6

What are the characteristics of mitochondrial genome?

Answer 6

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 )

Question 7

Important facts about genomes!

Answer 7

1. It is the total DNA content in a cell.
2. It contains all DNA including the protein coding DNA.
3. An organism has only 1 genome
4. The study of it is called genomics

Question 8

Important facts about genes!

Answer 8

1. It is only a segment of the DNA molecule
2. It contains only protein coding DNA.
3. thousands of genes in an organism .
4. The study of it is called genetics.

Question 9

What is the structure of dna?

Answer 9

Double helical.

Question 10

A nucleotide is made up of?

Answer 10

A phosphate group, sugar, and a base.

Question 11

Two nucleotides are linked together by what bonds and where?

Answer 11

By equal covalent bonds. Located between a sugar of one nucleotide and a phosphate group of another.

Question 12

What bonds link the 2 strands of dna together?

Answer 12

H bonds.

Question 13

Complementary base pairing occurs between 2 strands .

Answer 13

A-T / C-G

Question 14

Explain why the two strands of the dna are anti parallel?

Answer 14

5 to 3 on one strand and 3 to 5 on the other.

Question 15

How are such large dna fibers compactly packaged in a small nucleus?

Answer 15

Because of histone proteins. (H2A, H2B, H3, H4)

Question 16

These histone proteins form an Octomer and wraps the dna strand TWICE.

Answer 16

Each complex of histone proteins and dna wrapping around them are called

Question 17

Each complex of histone proteins and dna wrapping around them are called ?

Answer 17

Nucleosomes

Question 18

Nucleosomes are separated by a…..?

Answer 18

30 -bp linker dna.

Question 19

What histone protein binds on the linker site and protects the nucleosomes from becoming a mess / tangled.

Answer 19

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.

Question 20

What happens in mitotic cell division?

Answer 20

Linear DNA packing with histone proteins and forming supercoiled sister chromatid occurs in metaphase stage .

Question 21

What chromosomes are used in karyotyping? And why?

Answer 21

• metaphase chromosomes and it is for identifying the chromosomes number and structure abnormalities.
  Example of these abnormalities are:
• XO & XXY
• translocation.

Question 22

What happens when a doubled stranded dna is heated?

Answer 22

The h bonds start breaking

Question 23

Breaking a double stranded dna into single strands is known as?

Answer 23

DNA denaturation.

Question 24

What is renaturation?

Answer 24

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.

Question 25

Denaturation if a dna at particular temperature depends on?

Answer 25

G- C and A - T contents of a DNA.

Question 26

Why does A-T base pairs melt at about 70 C?

Answer 26

Bc / of weaker 2 H bonds.

Question 27

Why does C-G base pairs melt at about 95 C?

Answer 27

Bc / of stronger 3 H bonds.

Question 28

The temperature at which the DNA strands are half denatured (50%) is called the?

Answer 28

The melting temperature.

Question 29

Again melting temperature varies to each organism based on the?

Answer 29

G-C , A-T contents

Question 30

The denaturation and renaturation properties of dna are being exploited in many biological experiments including ?

Answer 30

1. Hybridization

2. Polymerase chain reaction (PCR)

Question 31

What is hybridization?

Answer 31

It is an experiment to identify the dna homology between two different organisms and or their genes of interest.

Question 32

What is PCR?

Answer 32

PCR uses denaturation and renaturation properties of a dna. It helps to amplify the target DNA sequences in large quantities.