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Flashcards in Intro to Medical Genetics Deck (64)
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1

A gene is a segment of DNA that encodes for a specific
a) protein
b) tRNA
c) rRNA
d) microRNA
e) all of the above

e

2

Define an allele

Alternative forms of a gene (DNA at a specific locus) that differ in sequence

3

Define a locus

A physical region of a chromosome; often used to refer to a segment of DNA that contains a specific gene

4

Homologous chromosomes are chromosomes that ______ during meiosis, ____ from each parent

pair, one

5

Are homologous chromosomes identical?

No, normally only a few base pair differences in each gene

6

Are sister chromatids identical?

Yes, two identical duplicated chromosomes joined by a single centromere

7

During which cell replication cycle would you find sister chromatids?

Metaphase

8

What are autosomes?

ANy chromosome that is not a sex chromosome

9

An organism with 4 copies of each chromosome would be ________

tetraploid

10

A human has 45 chromosomes in a cell. He is a _____________ (type of ploidy)

Aneuplod

11

A human has 69 chromosomes in a cell. He is a ____________ (type of ploidy)

Euploid - abnormal but still same number of each homologous chromosome

12

Germline cells are responsible for _____________________

production of gametes

13

What are gametes

haploid germ cells (sperm and ova)

14

What are zygotes

Two gametes fuse (during fertilization), diploid

15

Homologous chromosomes have _______ genes in ______ positions, but _______ alleles
(same/different)

same, same, different

16

Why is neonatal screening done?

To ID rare disorders that can cause brain damage or death if not treated early ie PKU

17

Describe prophase of mitosis

chromatin condenses (chromosomes with two chromatids) --> spindle forms --> nucleolus breaks down

18

Describe prometaphase of mitosis

spindle invades nuclear region, chromosomes move to equatorial plane

19

Describe metaphase of mitosis

Chromosomes at equatorial plane and centromeres divide

20

Describe anaphase of mitosis

poles move apart and chromosomes move towards destinations

21

Describe telophase of mitosis

Spindle breaks down --> chromatid uncoils --> nucleoli formed --> contractile ring causes cytokinesis

22

What is the product of cytokinesis in mitosis?

Two daughter cells, each genetically identical to parent cell

23

Describe prophase I of meiosis

Homologous chromosomes pair up and exchange fragments (cross over)

24

Describe metaphase I of meiosis

Homologous pairs line up at metaphase plate

25

Describe Anaphase I of meiosis

Homologues separate to opposite ends of cell, sister chromatids stay together

26

Describe Telophase I of meiosis

Newly formed cells are haploid, each chromosome has two (non-identical) sister chromatids

27

Meiosis II is very similar to mitosis. What are the two differences?

1) Haploid (2n) cells at beginning rather than diploid (4n)
2) Creates 4 haploid cells, with chromosomes having one chromatid each

28

What is the key difference between meiosis and mitosis?

During prophase homologous chromosomes synapse - pair up tightly and there is genetic exchange (evidenced by chiasmata)

29

Describe synapsis

Pairs of sister chromatids align according to homologous sequences and are bound together --> crossing over occurs

30

What is the product of crossing over? (type of chromosome)

recombinant!