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Flashcards in Basic Genetics Deck (48)
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1
Q

Number of autosomes in somatic cells

A

22 pairs = 44

2
Q

Number of sex chromosomes in somatic cells

A

1 pair = 2 (XX or XY)

3
Q

Normal chromosome complement is known as- ?

A

Diploid

4
Q

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) -?

A

Haploid

5
Q

Three copies of each chromosome are known as-?

A

Triploid

6
Q

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

A

Aneuploid

7
Q

What does divide chromosome into long arm & short arm?

A

Centromere

8
Q

Short arm symbol

A

p (= petit)

9
Q

Long arm symbol

A

q

10
Q

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

A

Acrocentric chromosomes

11
Q

What are the acrocentric chromosomes?

A

13, 14, 15, 21, 22

12
Q

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

A

Lyonisation

13
Q

In lyonisation, which X is selected as active?

A

Random selection

14
Q

In lyonisation, inactivated X chromosome is seen as-?

A

Barr body on microscopy

15
Q

A region of DNA that encodes protein

A

Gene

16
Q

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

A

Genome

17
Q

Site of a gene/particular DNA region in a chromosome

A

Locus

18
Q

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

A

Chromosome

19
Q

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

A

Alleles

20
Q

Sequence of amino acid-known as?

A

Codon

21
Q

Number and appearence of chromosome in the nucleus

A

Karyotype

22
Q

Karyotype of a normal person

A

46 XY or 46XX

23
Q

Any chromosome other than sex chromosome

A

Autosome

24
Q

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

A

Mitosis

25
Q

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

A

Meiosis

26
Q

Another name of meiosis

A

Reduction division

27
Q

Where does Meiosis occur?

A

Germ cells of the gonads

28
Q

Number of produced cells and chromosomes in Meiosis

A

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

29
Q

Division of Meiosis

A

Meiosis I and meiosis II

30
Q

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

A

Meiosis I

31
Q

Exchange of chromosome segments between homologous chromosomes - is called?

A

Crossing over

32
Q

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

A

In Meiosis I, before chromosomes are reduced in number

33
Q

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

A

Different to each other

34
Q

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

A

Due to recombination from crossing-over during meiosis I

35
Q

Time of onset of meiosis in male

A

Meiosis and spermatogenesis both start at puberty

36
Q

Time of onset of meiosis in female

A

Meiosis (replication of the chromosomes and crossing over) starts in foetal life

Oocytes remain suspended before the first cell division, until just before ovulation

37
Q

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

A

Reciprocal translocation

38
Q

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

A

Robertsonian translocation

39
Q

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

A

Balanced translocation

40
Q

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

A

Unbalanced translocation

41
Q

Common sex chromosome aneuploidies

A

Turner syndrome (45, XO)

Triple X syndrome (47, XXX)

Klinefelter syndrome (47, XXY)

47XYY males

42
Q

Common autosomal chromosome aneuploidies

A

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)

43
Q

Trisomy vs monosomy in autosomal chromosome aneuploidy

A

Trisomy is well tolerated than monosomy

3 trisomies are there which are compatible with life, but no whole autosome monosomies are compatible with life

44
Q

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

A

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

45
Q

Common Microdeletion syndromes

A

DiGeorge syndrome

Williams syndrome

46
Q

What are the Mendelian inheritances?

A

Autosomal dominant

Autosomal recessive

X-linked dominant

X-linked recessive

47
Q

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?

A

Genomic imprinting

48
Q

Common examples of genomic imprinting

A

The most commons:

Prader Willi syndrome

Angelman syndrome

Other commons:

Albright’s hereditary osteodystrophy

Beckwith-Wiedemann syndrome

Russell-Silver syndrome

Familial paraganglioma