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Foundations of Medicine > Chromosomes > Flashcards

Chromosomes Flashcards

1
Q

What is a chromosome?

A

A thread-like structure made up of DNA

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2
Q

Where are chromosomes found?

A

Nucleus of each cells

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3
Q

What is the role of chromosomes?

A

Allow DNA to be accurately copied during cell divison

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4
Q

How many chromosomes are in each cell?

A

46 individual chromosomes
23 pairs of chromosomes

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5
Q

What determines gender?

A

Every egg has an X sex chromosome; a sperm can have either an X or a Y sex chromosome.

If the sperm that fertilizes an egg has an X chromosome, the baby is female; if it has a Y chromosome, the baby will be a boy.

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6
Q

What is the main protein present in a chromosome?

A

Histones - largely positive globular proteins

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7
Q

What is the role of histones?

A

Organise and condense DNA tightly so that it fits into the nucleus

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8
Q

What is chromatin?

A

Tightly coiled combination of DNA and proteins

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9
Q

What are telomeres?

A

DNA-protein structures that form protective caps at the end of chromosomes.

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10
Q

What are telomeres repeats of?

A

5’-TTAGGG-3’ repeats

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11
Q

What are centromeres?

A

The region of a chromosome to which the microtubules of the spindle attach, via the kinetochore, during cell division.

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12
Q

What do centromeres help with?

A

Helping the cell divide up its DNA during division (mitosis and meiosis)

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13
Q

What are centromeres made up of?

A

Repetitive DNA sequences

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14
Q

How are negatively charged DNA neutralised?

A

Positive charged histone proteins

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15
Q

Advantage of DNA packing

A

Inactive DNA can be folded into inaccessible locations until required

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16
Q

What is chromosome analysis?

A

Chromosome analysis is a test to look at the chromosomes in a sample of cells.

17
Q

What can chromosome analysis help with?

A

Identify genetic abnormalities as the cause of a condition or disease.

The test can count the number of chromosomes present, and look for any structural abnormalities in the chromosomes.

18
Q

What is G-banding?

A

A technique used in cytogenetics to produce a visible karyotype by staining condensed chromosomes.

19
Q

What does G-banding allow?

A

Allows each chromosome to be identified by its characteristic banding pattern

20
Q

How is G banding carried out?

A

Treating aged metaphase preparations with a protease (trypsin) before Giemsa stain is applied to generate a reproducible banding pattern.

21
Q

What does FISH do?

A

A procedure that creates a map of the genetic material in human cells.

22
Q

What can FISH analysis be used for?

A

Understanding a variety of chromosomal abnormalities and other genetic mutations

23
Q

What are the types of FISH probes?

A

Unique sequencing probes
Centrometric probes
Telomeric probes
Whole chromosome probes

24
Q

What are centromeric probes used for?

A

Determining chromosome number

25
Q

What are telomeric probes used for?

A

Detecting subtelomeric rearrangements - often present in children with unexplained mental retardation

26
Q

What are whole chromosome probes?

A

Cocktail of probes covering different parts of a particular chromosome - used with different fluorescent dyes

27
Q

What are whole chromosome probes used for?

A

Detecting translocations and rearrangements

28
Q

What are structural abnormalities in chromosomes?

A

Alteration in chromosome’s structure

29
Q

What are deletion abnormalities?

A

A portion of the chromosome is missing or deleted.

30
Q

What are duplication abnormalities?

A

A portion of the chromosome is duplicated, resulting in extra genetic material.

31
Q

What are translocation abnormalities?

A

A portion of one chromosome is transferred to another chromosome.

32
Q

What are inversion abnormalities?

A

A portion of the chromosome has broken off, turned upside down, and reattached.

As a result, the genetic material is inverted.

33
Q

What are ring abnormalities?

A

A portion of a chromosome has broken off and formed a circle or ring.

This can happen with or without loss of genetic material.

34
Q

What are the two types of translocation?

A

Reciprocal
Robersonian

35
Q

What happens in a reciprocal translocation?

A

Segments from two different chromosomes have been exchanged.

36
Q

What happens in a Robersonian translocation?

A

An entire chromosome has attached to another at the centromere.

37
Q

What are the two types of chromosomes?

A
  • Sex chromosomes, which determine male or female gender
  • Autosomes, which are all ofthe other chromosomes (chromosome pairs 1 through 22) or non-sex chromosomes

Foundations of Medicine (56 decks)

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