Basic Genetics

Question 1

Number of autosomes in somatic cells

Answer 1

22 pairs = 44

Question 2

Number of sex chromosomes in somatic cells

Answer 2

1 pair = 2 (XX or XY)

Question 3

Normal chromosome complement is known as- ?

Answer 3

Diploid

Question 4

Genomes with a single copy of each chromosome are known as-?

OR

Half of full set of genetic material in the gamete (egg/sperm) -?

OR

Single set of chromosomes in the gamete (egg/sperm) -?

Answer 4

Haploid

Question 5

Three copies of each chromosome are known as-?

Answer 5

Triploid

Question 6

A karyotype with too many or too few chromosomes + total is NOT multiple of 23 >> is known as-?

Answer 6

Aneuploid

Question 7

What does divide chromosome into long arm & short arm?

Answer 7

Centromere

Question 8

Short arm symbol

Answer 8

p (= petit)

Question 9

Long arm symbol

Answer 9

q

Question 10

If centromeres are located at one end, the chromosomes are known as-?

Answer 10

Acrocentric chromosomes

Question 11

What are the acrocentric chromosomes?

Answer 11

13, 14, 15, 21, 22

Question 12

If a cell contains more than one X chromosome, but only one is active >> known as -?

Answer 12

Lyonisation

Question 13

In lyonisation, which X is selected as active?

Answer 13

Random selection

Question 14

In lyonisation, inactivated X chromosome is seen as-?

Answer 14

Barr body on microscopy

Question 15

A region of DNA that encodes protein

Answer 15

Gene

Question 16

Complete set of gene of an organism + the intervening DNA sequences

Answer 16

Genome

Question 17

Site of a gene/particular DNA region in a chromosome

Answer 17

Locus

Question 18

Self replicating genetic structure of cells containing the cellular DNA that bears the linear array of genes in its nucleotide sequence

Answer 18

Chromosome

Question 19

Alternative form of gene found at the same locus on a chromosome >> known as-?

Answer 19

Alleles

Question 20

Sequence of amino acid-known as?

Answer 20

Codon

Question 21

Number and appearence of chromosome in the nucleus

Answer 21

Karyotype

Question 22

Karyotype of a normal person

Answer 22

46 XY or 46XX

Question 23

Any chromosome other than sex chromosome

Answer 23

Autosome

Question 24

Diploid to diploid cell division

= mother diploid cell to daughter diploid cells

Nuclear chromosomes are genetically identical both to each other & to the original parent cell

Answer 24

Mitosis

Question 25

**Diploid to haploid cell division** **= Diploid mother cells to haploid daughter cells** **= Nuclear chromosome in daughter cells are half than the mother cells & genetically different from each other**

Answer 25

**Meiosis**

Question 26

**Another name of meiosis**

Answer 26

**Reduction division**

Question 27

**Where does Meiosis occur?**

Answer 27

**Germ cells of the gonads**

Question 28

**Number of produced cells and chromosomes in Meiosis**

Answer 28

**4 haploid daughter cells, each containing one set of chromosome pair**

Question 29

**Division of Meiosis**

Answer 29

**Meiosis I and meiosis II**

Question 30

**When are the chromosomes reduced in number? Meiosis I or Meisosis II?**

Answer 30

**Meiosis I**

Question 31

**Exchange of chromosome segments between homologous chromosomes - is called?**

Answer 31

**Crossing over**

Question 32

**When does Crossing over occur? in Meiosis I or Meiosis II?**

Answer 32

**In Meiosis I, before chromosomes are reduced in number**

Question 33

**All four daughter cells are genetically identical to each other or different?**

Answer 33

**Different to each other**

Question 34

**Why are all 4 haploid daughter cells in Meiosis genetically different to each other?**

Answer 34

**Due to recombination from crossing-over during meiosis I**

Question 35

**Time of onset of meiosis in male**

Answer 35

**Meiosis and spermatogenesis both start at puberty**

Question 36

**Time of onset of meiosis in female**

Answer 36

**Meiosis (replication of the chromosomes and crossing over) starts in foetal life** **Oocytes remain suspended before the first cell division, until just before ovulation**

Question 37

**Exchange of genetic material between non-homologous chromosomes- is called?**

Answer 37

**Reciprocal translocation**

Question 38

**Fusion of two acrocentric chromocomes at their centromeres- is called?**

Answer 38

**Robertsonian translocation**

Question 39

**If no chromosomal material has been lost or gained overall- is called?**

Answer 39

**Balanced translocation**

Question 40

**If chromosomal material has been lost or gained overall- is called?**

Answer 40

**Unbalanced translocation**

Question 41

**Common sex chromosome aneuploidies**

Answer 41

**Turner syndrome (45, XO)** **Triple X syndrome (47, XXX)** **Klinefelter syndrome (47, XXY)** **47XYY males**

Question 42

**Common autosomal chromosome aneuploidies**

Answer 42

**Down syndrome (trisomy 21)** **Edward syndrome (trisomy 18)** **Patau syndrome (trisomy 13)** (These 3 are also example of non-dysjunction/trisomies) (These 3 aneuploides are compatible of life) (21, 18, 13 are the least gene-rich chromosomes)

Question 43

**Trisomy vs monosomy in autosomal chromosome aneuploidy**

Answer 43

**Trisomy is well tolerated than monosomy** **3 trisomies are there which are compatible with life, but no whole autosome monosomies are compatible with life**

Question 44

**Why are trisomies 21, 18, 13 compatible with life?**

Answer 44

**Because chromosome 21, 18, 13 are 3 least gene rich chromosomes**

Question 45

**Common Microdeletion syndromes**

Answer 45

**DiGeorge syndrome** **Williams syndrome**

Question 46

**What are the Mendelian inheritances?**

Answer 46

**Autosomal dominant** **Autosomal recessive** **X-linked dominant** **X-linked recessive**

Question 47

**For most genes, both copies (maternal/paternal) are expressed.** **But for some genes, either the maternal or paternal copy is used- this phenomenon is known as?**

Answer 47

**Genomic imprinting**

Question 48

**Common examples of genomic imprinting**

Answer 48

The most commons: **Prader Willi syndrome** **Angelman syndrome** Other commons: **Albright's hereditary osteodystrophy** **Beckwith-Wiedemann syndrome** **Russell-Silver syndrome** **Familial paraganglioma**