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Cell Biology > Studying Chromosomes > Flashcards

Studying Chromosomes Flashcards

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1
Q

What are chromosomes?

A

Long DNA molecule with part or all of the genetic material of an organism.

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2
Q

What is cytogenetics?

A
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3
Q

What is X-inactivation?

A

One of the two X chromosomes in each of the female’s somatic cells is inactive

The inactivated X chromosomes become heterochromatin

The inactivated X chromosome will condense into a so-called Barr-body

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4
Q

What does a G-banding karyotype give information about?

A

The number of chromosomes

The structure of chromosomes

Regions of euchromatin and heterochromatin

Chromosomal aberrations and translocations

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5
Q

What are 4 complete sets of chromosomes in a single cell called?

A

Tetraploidy

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6
Q

Patients with Down Syndrome have an extra chromosome 21, what is this referred to as?

A

Trisomy 21

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7
Q

Give an example of monosomy

A

45, X

(any number at the beginning)

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8
Q

What is reciprocal translocation?

A

Two non-homologous chromosomes exchange parts

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9
Q

Define genome

A

All of an organism’s genetic information in DNA (or in some viruses, RNA)

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10
Q

What are genes?

A

Genes are a small part of the genome coding for many different RNAs including mRNA for proteins and rRNA for ribosomes

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11
Q

What is Chromatin?

A

DNA and associated proteins that make up the chromosomes

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12
Q

What is forward genetics and what is reverse genetics?

A

Forward: Phenotype to Genotype

Reverse: Genotype to Phenotype

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13
Q

Explain what karyotyping is

A

The study of chromosomes of a single organism, geneticists arrange micrographs of the stained chromosomes in homologous pairs of decreasing size to produce a karyotype

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14
Q

How are metaphase chromosomes classified?

A

Number of chromosomes

Size of chromosomes

Morphology of chromosomes

Banding pattern

Regions of heterochromatin and euchromatin

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15
Q

What 2 chemical stains are used to aid karyotyping?

A

Quinacrine (Q banding) and Giemsa (G-banding) can be used to differentially stain chromosomes to reveal species-specific banding patterns.

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16
Q

Explain Giemsa staining (G-banding)

A

The short arm is designated ‘p’ (petite)

Each band has an identifier number

The long arm is designed ‘q’ (the next letter in the alphabet)

17
Q

Explain what metacentric, submetacentric, and acrocentric chromosomes are

A

Metacentric = chromosomes have short and long arms of roughly equal length with the centromere in the middle

Submetacentric = Chromosomes have sort and long arms of unequal lengths with the centromere more towards one end

Acrocentric = Chromosomes have a centromere very near to one end and have very small short arms. They frequently have secondary constrictions on the short arms that connect very small pieces of DNA, called stalks and satellites, to the centromeres. The stalks-satellites contain genes that code for rRNA

18
Q

Explain the term ploidy cells

A

Number of chromosomes in a cell

Two sets of chromosomes (diploid cell)

One set of chromosomes (haploid cell)

Humans have 23 Paris of chromosomes (46 in total)

22 Paris are autosomes and 1 pair is sex chromosomes (XX and XY)

19
Q

Explain the term diploid cells

A

Diploid cells contain 2 complete sets (2n) of chromosomes

Diploid cells reproduce by mitosis making daughter cells that are exact replicas

Skin, blood, muscle cells (somatic cells)

20
Q

Explain the term haploid cells

A

Haploid cells have half the number of chromosomes (n) as diploid - i.e a haploid cell contains only one complete set of chromosomes

Haploid cells are the result of the process of meiosis, a type of cell division give rise to haploid germ cells

Cells used in sexual reproduction - sperm and egg (gametes)

21
Q

Explain the term polyploidy

A

Polyploidy is multiple sets of chromosomes present

Common in plants, but are rare in animals

In humans, it is pathological and leads to early death

22
Q

Give some visible alterations of chromosomes produced by chromosome-specific mechanisms

A

Constitutional changes (germline in origin) all the cells/tissues hold the same abnormality

Somatic changes (e.g. certain cancers)

Numerical changes - cells with an extra chromosome or a deficiency in chromosomes

Structural changes

23
Q

Explain what clinical cytogenetics is

A

The study of the relationship of chromosomal alterations and genetic disease in humans

24
Q

Explain what Trisomy 12 (T12), Trisomy 13 (T13) and Trisomy 18 (T18) are. How can we find out if someone has these?

A

T12 - Down Syndrome

T13 - Patau’s Syndrome

T18 - Edward;s Syndrome

Prenatal Screening

Cell Biology (11 decks)

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