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Top2 BCM > Lecture 1 > Flashcards

Lecture 1 Flashcards

1
Q

Genome

A

Total amount of genetic material in a chromosome set

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2
Q

Gene

A

DNA sequence coding for a protein or a functional RNA

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3
Q

UTR

A

Non-coding region (portion not translated) of mRNA molecule

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4
Q

Gene fragment

A

Non-functional gene relic consisting of a short isolated region from within a gene

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5
Q

Pseudogenes

A

DNA sequences that resemble functional genes but are non-functional in that they no longer encode functional proteins or are otherwise no longer expressed in the cell

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6
Q

Transposon

A

DNA segment that can move from one position in the genome to another (non-homologous) position

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7
Q

Tandem repeat

A

A repeated end-to-end duplication of a core DNA sequence at a defined locus

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8
Q

Microsatellite

A

An array of very short tandem repeats (2-6 base pairs each).

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9
Q

Minisatellite

A

Similar to microsatellite, but repeat unit is larger (usually 10-60bp)

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10
Q

Chromatin

A

Mass of genetic material composed of DNA and proteins that condense to form chromosomes. The building block of chromatin is the nucleosome

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11
Q

Nucleosome

A

Short length of DNA (147bp) wrapped around octameric core of four histone proteins (2 copies each of histone H2A, H2B, H3 and H4)

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12
Q

Where is the majority of the genome in Euk cells?

A

As chromosomes in the nucleus

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13
Q

What is contained within a genome? (7)

A

Genes (exons and introns)
Regulatory regions (gene promoters, terminators)
Centromere
Telomere
Rep Origins
Junk DNA (simple repetitive regions, but not centromeres/telomeres) (Transposons)

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14
Q

What are transposons?

A

DNA segment that can move from one position in the genome to another (non-homologous) position. Jumping genes, mobile genetic elements

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15
Q

How much of the 3200Mb Human Genome is for Genes?

A

48Mb

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16
Q

Describe the gene in terms of units of heredity?

A

Fundamental physical unit of hereditary which occupies a specific chromosomal locus

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17
Q

The 5’ to 3’ strand is described as what?

A

Top, Forward, Watson

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18
Q

The 3’ to 5’ strand is described as what?

A

Bottom, Reverse, Crick

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19
Q

What are exons?

A

Sequences that are present in the mature mRNA

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20
Q

What are introns?

A

Sequences that interrupt eukaryotic genes, and are spliced out of the mRNA

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21
Q

What is the average number of exons per human gene?

A

10 exons

22
Q

What does the human B-globin gene encode and how many exons does it have?

A

Encodes a hemoglobin protein subunit, contains 3 exons

23
Q

UTR extends from what to what in 5’ and 3’?

A

5’UTR extends from the 5’ cap to the start codon.

3’UTR extends from the translation stop codon to the start of the poly A tail.

24
Q

Draw the genome tree

A

Human Genome
Genes and gene related sequences, Intergenic sequences (non coding)
Genes and related sequences
introns, pseudo, gene fragments

25
Q

What are the 2 main types of pseudogenes?

A

Processed, conventional (unprocessed)

26
Q

Define processed pseudogenes

A

Arise from a mRNA copy of the gene being converted back to DNA (reverse transcription) which is inserted into another region of the genome.
Do not contain intron sequences, nor promoter sequences. Not usually transcribed

27
Q

Define conventional pseudogenes

A

Genes that accumulated mutations (changes in the DNA sequence) over time which make them non-functional

28
Q

Types and effects of mutation that can lead to loss of functions. List 5 of them (conventional pseudogenes)

A

1) SNPs (single nucleotide polymorphism) still look like the original gene
2) Non-synonymous mutuation that cause amino acid substitution(s) of key regions (Active site)
3) Mutation(s) in the promoter sequence that cause loss of gene expression
4) Mutation in introns splice-site sequences that cause loss of splicing
5) Mutation that create in-frame premature stop codons

29
Q

What categories come under intergenic sequences (non-coding)?

A

Interspersed repeats - Transposons, LINEs, SINEs, LTR elements
Other intergenic regions - Microsatellities and Various

30
Q

What are the retrotransposons?

A

LINEs, SINEs, LTR elements

31
Q

Where are interspersed repeats?

A

They are at diff locations through the genome

32
Q

Transposons are potential what??

A

Mutagens, they have disrupted a gene and caused disease

33
Q

Transposons eventually become what?

A

inactive and no longer move

34
Q

Describe the two types of movements of transposable elements?

A

Conservative, when there is movement without duplication. Transposon has moved from old site and inserted into a new site.

Replicative, movement with duplication. Copies of element old and new sites

35
Q

retrotransposons

a) are what?
b) undergo what process?
c) what enzymes are involved?

A

a) LINEs, SINEs and LTR elements
b) they are transcribed and an RNA intermediate is produced. The intermediate undergoes reverse transcription which is then inserted into another chromsome
c) Reverse transcription andTy1

36
Q

Microsatellites are known as what?

A

Short tandem repeats (STRs) or simple sequence repeats (SSRs)

37
Q

A common microsatellite is what?

A

A (CA)n repeat, where n is the number of repeats and this can vary between alleles and among individuals in population. Makes up 0.25% of the human genome

38
Q

Microsatellites are widely known for what?

A

Their use in DNA profiling/fingerprinting

39
Q

What non coding regions must a chromosome contain?

A

2 telomers, centromere, replication of origin

40
Q

Name 3 reasons as to why the genome is packed into chromosomes?

A

Compact from of DNA which fits inside the cell
Protects the DNA from damage
DNA packaged in chromosomes can be transmitted efficiently to both daughter cells during division.

41
Q

Name 3 other reasons for the genes being organised into chromosomes?

A

Regulates gene expression
DNA replication
Recombination

42
Q

Briefly name the processes of DNA packaging

A

DNA double helix > Nucleosomes form of chromatin > 30nm chromatin fiber > section of chromosome in extended form > condensed section of chromosome > entire chromosome

43
Q

most transposable elements possess what type of repeats terminally?

A

Temrinal inverted repeats and generate flanking direct repeats one each side of the point of insertion into target DNA.

44
Q

Describe the mechanism for transposable elements?

A

DNA transposon has Inverted terminal repeats and then direct repeats. The transposase enzyme binds to the transposon DNA at either end of the DNA. These two enzymes then bind together to cleave the dna. The cleaved dna is then transferred and inserted into another strand.

45
Q

look at Alu for SINE

A

okaky

46
Q

Minisatellites are found where?

A

At the sub telomeric region of chromosomes. Many of the remaining are associated with centromeric loci.

47
Q

what is the building block of chromatin?

A

Nucelosome

48
Q

define chromatin

A

Mass of genetic material composed of dna and proteins that condense to form chromosomes

49
Q

What are the 2 general forms of chromatin?

A

Euchromatin - less condensed and can be transcribed.

Heterochromatin - hgihly condensed

50
Q

What is a nucleosome compose d of?

A

Short length of DNA wrapped aorund an octameric core of 4 histone proteins. two copies of each histone

Top2 BCM (9 decks)

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