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Genetics Lab > Lab 1 > Flashcards

Lab 1 Flashcards

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Biology 101 flashcards
1
Q

What is a chromosome?

A

Structures made of DNA and protein that contain numerous genes which encode the proteins in our bodies

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2
Q

What is a karyotype & when is it done?

A

A karyotype is a photograph or diagram of all the
chromosomes in a cell arranged in a particular order.
Done at metaphase so the dyads are more condensed and easier to visualize.

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3
Q

What does a somatic cell contain?

A

A somatic cell contains 44 autosomes (nonsex
chromosomes), or 22 homologous pairs of
autosomes, and 2 sex chromosomes.

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4
Q

What is a homolog?

A

A single unduplicated chromosome. Each homolog is similar but not
identical to the other homolog in the pair

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5
Q

Another name for tetrad?

A

Bivalent & duplicated homologous chromosome pair.

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6
Q

Another name for dyad?

A

Duplicated chromosome

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7
Q

What is a centromere?

A

A condensed region on the chromosome that provides the attachment site for the kinetochore

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8
Q

What does colchicine do?

A

Inhibits microtubule formation required to form the spindle fibers so that mitosis does not proceed past metaphase.

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9
Q

Turner syndrome

A

Only one X and no Y chromosome.

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10
Q

How are chromosomes distinguished from one another?

A

Size, Location of centromere, and banding patterns.

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11
Q

Location of centromere:

A

Metacentric – centromere is near the middle

Submetacentric – centromere is slightly off center

Acrocentric – centromere is significantly off center

Telocentric – centromere is at the end.

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12
Q

What are primary constrictions?
What are secondary constrictions?

A

Centromere
They are usually the site of rRNA gene.

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13
Q

How are chromosomes stained?

A

They are stained using a Giesma stain

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14
Q

Chromosome abnormalities involving one chromosome?

A

Deletion: part of the chromosome is absent.
Duplication: section of chromosome is repeated
Inversion: section of chromosome is upside down.

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15
Q

Chromosome abnormalities involving two chromosomes?

A

Simple Translocation: A piece of a chromosome is attached to another chromosome.
Reciprocal Translocation: Two different chromosomes exchange pieces.

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16
Q

What is crossing over?

A

Genetic exchange that occurs during meiosis. It occurs between two chromosomes that are the same number.
Occurs between duplicated chromosomes in a tetrad.

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17
Q

Familia type of Down syndrome

A

Not caused by nondisjunction.
Caused by Translocation.
Involves chromosomes 14 & 21.

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18
Q

Hypotonic Solution

A

Low solute concentration, high water concentration.
In karyotyping, they make the cell swell, this separates the chromosome so that they are easier to count.

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19
Q

What is Nondisjunction?

A

Failure of chromosomes to separate normally during cell division.

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20
Q

Two Types of Chromosomal Inversion-

A

Pericentric Inversion- Includes the centromere.
Paracentric Inversion- Doesn’t include the centromere

21
Q

Position Effect

A

The expression of a gene can be altered, and the gene itself remains intact.
With a position effect, you are changing the physical
position of the gene on the chromosome, and that
change affects the expression of the gene.

22
Q

Silencer/Condensed region

A

Example of a position effect.
Condensed region: Genes in highly
condensed regions of the chromosome are not expressed well.
Silencer: Genes are not expressed when they should be.

23
Q

Enhancer

A

A sequence that increases transcription, so the gene would be overexpressed.

24
Q

What are telomeres?

A

Repeated sequences on the ends of chromosomes that prevents chromosomal ends from attaching to one another.

25
Q

Reactive end

A

When the telomere breaks, a reactive end is formed. The reactive ends can be joined by DNA repair enzymes to create translocation between two nonhomologous chromosomes.

26
Q

Why might down syndrome occur? (Trisomy 21)

A

It might occur when crossing over does not take place between homologous chromosomes during meiosis during prophase 1.

27
Q

What is Robertsonian Translocation?

A

Translocation that can occur between any acrocentric chromosomes that are numbered.
This can lead to down syndrome.
Fertilization with gamete 1: Monosomy 21 develops
Fertilization with gamete 2: Familial down syndrome.

28
Q

A type of Hemophilia occurs _____

A

On genes that encode blood clotting factors.
The gene is located on the X chromosome.
It involves an Inversion.

29
Q

The first step of gene expression:

A

Transcription.

30
Q

When a chromosome that is not a sex chromosome is lost, it is always lethal. (True/False)

A

True

31
Q

What is nondisjunction?
what can it result to?

A

An event in which the chromosomes do not segregate properly.
This can result in a change in chromosome number.

32
Q

What is an alloploid organism?

A

An organism that contains sets of chromosomes from two or more species.

33
Q

Types of nondisjunction?

A

Meiotic non-disjunction: Occurs during meiosis.
Mitotic non-disjunction: Occurs during mitosis.

34
Q

Ways in which chromosome numbers can vary?

A

Mitotic non-disjunction
Meiotic non-disjunction
Alloploid.

35
Q

Complete nondisjunction:

A

All chromosomes undergo nondisjunction and migrate to one of the daughter cells.

36
Q

When do abnormalities in chromosomes normally occur?

A

After fertilization takes place.

37
Q

What is mosaicism?

A

When an organism contains a subset of cells that are genetically different from those of the rest of the organism.
This depends on the timing and location of the original abnormal event.

38
Q

What is autopolyploid?

A

An increase in the number of chromosomes set within a single species.

39
Q

what is a Metacentric chromosome?

A

A chromosome that has equally centered centromere with arms with equal lengths.

40
Q

what is a sub-metacentric chromosome?

A

A chromosome that has arms a bit off-centred, with arms that are distinctly unequal in length.

41
Q

what is an acrocentric chromosome?

A

Centromeres are located nearer to one end than to the other. The arms are unequal in length.

42
Q

What is used to show karyotype bands?

A

Giemsa Bloodstain.
G-Q-R bands.

43
Q

Each homolog is ________ but not
_________to the other homolog in the pair

A

Similar; Identical

44
Q

What is a centromere

A

A condensed region on the chromosome that
provides the attachment site for the kinetochore.

45
Q

Kinetochore:

A

Group of proteins that attach to the centromere. They
pull the sister chromatids apart during cell division.

46
Q

How to distinguish chromosomes from one
another:

A

Size, banding pattern & Location of centromere.

47
Q

Karyogram

A

The display of the karyotype

48
Q

What causes cru Du Chat?

A

Chromosomal deletion of chromosome 5.
Region on p arm is deleted.

Genetics Lab (6 decks)

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