Genetics

Question 1

What is genetics?

Answer 1

Genetics is the study of genes, genetic variation, and heredity in organisms.

Question 2

Who is the Father of Genetics?

Answer 2

Gregor Mendel

Question 3

What is Deoxyribose Nucleic Acid (DNA)?

Answer 3

It is the molecule that carries the genetic information for the development and functioning of an organism.

Question 4

What is the DNA structure like?

Answer 4

It has a sugar-phosphate backbone and information contained in the sequence of bases.
The strands pair up in an antiparallel fashion.

Question 5

DNA is replicated, and it is always read…

Answer 5

In the 5’ —-> 3’ direction

Question 6

What does the double helix of DNA consist of?

Answer 6

Consists of two strands running in the opposite direction to each other.

Question 7

What are the bonds formed between bases and what do they do?

Answer 7

Hydrogen bonds between the bases link the strands

Question 8

What are the names of the bases?

Answer 8

Adenine – Thymine
Guanine – Cytosine

Question 9

What are purines and two examples?

Answer 9

One of two chemical compounds cells use to make DNA and RNA building blocks.
-Adenine and Guanine

Question 10

What are pyrimidines, and three examples?

Answer 10

A nitrogenous base similar to benzene (a six-membered ring)
-Thymine, Cytosine, and Uracil

Question 11

What is RNA?

Answer 11

It stands for Ribonucleic Acid, and it is a single-stranded molecule.

Question 12

What are the two main differences between RNA and DNA?

Answer 12

• The sugar in the backbone is Ribose, instead of deoxyribose, and the base Uracil is used instead of Thymine.

Question 13

How many bases does the human genome have, and how many encode for genes?

Answer 13

The human genome has approximately 3 billion bases, although only a small proportion of them (1-2%) encode genes.

Question 14

What are histones?

Answer 14

A type of protein found in chromosomes. Histones bind to DNA, help give chromosomes their shape, and help control the activity of genes.

Question 15

What does the structure of DNA with histones resemble?

Answer 15

A ball of string

Question 16

What is the structure of histone, and what is its function?

Answer 16

Highly basic positively charged octamer. and it makes the DNA coil further to make the chromosomal structure.

Question 17

What does condensation do to the DNA?

Answer 17

Condensation of DNA controls gene function. Tightly coiled DNA
(condensed) is less transcriptionally active.

Question 18

What chromosomes are all present in the cells?

Answer 18

22 pairs of chromosomes and the sex chromosomes are present in each cell.

Question 19

Define DNA replication

Answer 19

DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule.

Question 20

A DNA strand can be replicated in 2 directions, true or false?

Answer 20

False. A DNA strand can only be replicated in one direction.

Question 21

After the strands are separated and unwound, what happens to the leading and lagging strands?

Answer 21

• The leading strand has bases added in the 5’ to 3’ direction by a DNA polymerase.
  -On the lagging strand, short stretches of DNA are synthesized as it unwinds (called Okazaki fragments), and these are then joined by
  a DNA ligase.

Question 22

What are Okazaki fragments?

Answer 22

Short sequences of DNA nucleotides are synthesized discontinuously and later linked together by the enzyme DNA ligase to create the lagging strand during DNA replication.

Question 23

What is Helicase?

Answer 23

DNA helicases catalyze the disruption of the hydrogen bonds that hold the two strands of double-stranded DNA together.

Question 24

What do the Primase, RNA primer, and DNA polymerase do?

Answer 24

Primase: Synthesizes RNA primers during DNA replication.
RNA primer: Primer RNA is RNA that initiates DNA synthesis.
DNA polymerase: Adds nucleotides to the three prime (3’)-ends of a DNA strand, one nucleotide at a time.

Question 25

What does ligase do?

Answer 25

Joins DNA fragments together, 'the gluer'

Question 26

What enzyme prevents the supercoiling of DNA?

Answer 26

Topoisomerase.

Question 27

What are SSB proteins?

Answer 27

-Stands for single-stranded binding proteins. These proteins bind to the DNA to prevent them from joining together again.

Question 28

What is mitosis, and what happens to one parent cell?

Answer 28

The process of somatic cell division. One parent cell becomes two almost genetically identical daughter cells.

Question 29

What are the stages of mitosis?

Answer 29

Interphase. Stage 1- Prophase Stage 2- Metaphase Stage 3- Anaphase Stage 4- Telophase Cytokinesis.

Question 30

What happens in the Interphase, and in what part of the cycle may the cell be found?

Answer 30

The cells look normal at this stage. The cell may be in G0, G1, or S phase in the cell cycle.

Question 31

When is DNA replicated? (In what phase?)

Answer 31

S phase

Question 32

What happens in prophase?

Answer 32

In Prophase, the chromosomes condense and form part of the mitotic spindle.

Question 33

What happens in metaphase?

Answer 33

In Metaphase, the chromosomes line up in the center of the dividing cell. Microtubules are attached to each chromosome centromere.

Question 34

Draw the structure and name the three elements formed by microtubules.

Answer 34

Kinetochore, Microtubule and Centromere

Question 35

What happens in the anaphase?

Answer 35

At Anaphase, the duplicated chromosomes are separated by contraction of the microtubules.

Question 36

What happens in telophase?

Answer 36

During Telophase, the chromosomes reach the poles of the cell, and the two cells separate (Cytokinesis). The chromosomes decondense and form part of the nucleus once more.

Question 37

What is cytokinesis?

Answer 37

Cytokinesis is the physical process of cell division, which divides the cytoplasm of a parental cell into two daughter cells.

Question 38

What is meiosis?

Answer 38

Meiosis in humans only occurs during gamete production.

Question 39

What are the stages in meiosis I, and what happens in each?

Answer 39

Interphase: Cells are normal. Prophase I: During Prophase in Meiosis I, homologous chromosomes pair, and there is a crossing over between the homologous chromatids. Anaphase I: Chromosomes are pulled apart by the contraction of the microtubules. Telophase I: Chromosomes reach the poles of the cell, and cytokinesis occurs. Now you have two daughter cells.

Question 40

What happens in meiosis II?

Answer 40

In Meiosis II, the second round of cell division leaves four haploid daughter cells.

Question 41

What are the stages of meiosis?

Answer 41

Prophase II Metaphase II Anaphase II Telophase II Daughter cells!

Question 42

What is the normal chromosome structure? Draw it and label it.

Answer 42

Telomere, Short Arm (p Arm), Centromere, Long arm (q Arm).

Question 43

What are sister chromatids?

Answer 43

Two chromatids held together

Question 44

What are the three types of chromosomes?

Answer 44

1. Submetacentric: Superior ones are slightly smaller. 2. Metacentric: telomere close to the middle, with a shorter “p” arm and longer “q” arm 3. Acrocentric: centromere at one end, with only satellite DNA on the short “p” arm.

Question 45

What three things are chromosomes recognised by?

Answer 45

Their size, the position of the centromere and their banding pattern.

Question 46

What is banding??

Answer 46

Chromosome banding refers to alternating light and dark regions along the length of a chromosome, produced after staining with a dye.

Question 47

When are chromosomes visualized?

Answer 47

Metaphase