Modul 1 Flashcards

Question

nogle gener har mere end en promoter

Answer 1

alternative promotorer. Der kan således være mulighed for at lave forskellige RNA ud fra et gen.

Answer 2

pr definition praecis der hvor transkription starter

Answer 3

men transskriberer et nyt RNA 5'-3' direktion.

Answer 4

- sense strand - kodende

Answer 5

- anti sense - template - ikke kodende

Answer 6

RNA bliver klippet over i 3' ende efter Poly A signal, og så påsat PolyA tale (ca 200x A)

Answer 7

donor splice sites (GT) mellem exon - intron sekvenser Acceptor splice site (AG) mellem intron - exon sekevenser

Answer 8

co-transskriptionelt vha ‘splice-factors’ der binder RNA ‘splice sites’ hvorefter intron sekvenser bliver fjernet vha ”klippe og klistre” mekanisme.

Answer 9

exons og kaldes mRNA

Answer 10

kan også findes i introns, der kan vaere flere af dem og raekkefølgen kan også variere.

Answer 11

sammen med transskription, og derved mRNA ekspression niveauet i forhold til maengede, sted og tid. nogle TF er udtrykt i alle vaev, og andre er vaev-specifikke.

Answer 12

Histoner er proteiner med den egenskab at de (8 stk) kan danne en ”kugleformet” struktur hvor omkring ca 140-150 bp dobbeltstrenget DNA kan vikles rundt. En sådan DNA/protein pakningsenhed kaldes et nukleosom. Genomisk DNA er i en cellekerne pakket i form af nukleosomer, og denne pakning kaldes **kromatin**.

Answer 13

åben kromatin

Answer 14

lukket kromatin

Answer 15

Kvinder, 46XX, men store dele af det ene X kromosom er transskriptionelt inaktivt pga pakning som heterokromatin. (**inaktiv X kromosom kan ses som Barr-Bodies under et mikroskop**).

Answer 16

cytoplasm (inde i ribosomer)

Answer 17

5'-3' direktion

Answer 18

17-27 nukleotider (baser) lange RNA. Der findes mange miRNA gener. antiparallel og komplementaer binding af miRNA (oftest i mRNA 3' UTR), kan haemme translation samt stabilitet af mRNA.

Answer 19

vigtigst for mRNA binding, så hele miRNA sekvens behøves **IKKE** vaere komplementaer til mRNA.

Answer 20

fin tuning af gen-ekpression. miRNA regulering betyder at maengden af mRNA ikke nødvendigvis er direkte proportionel med maengden af det korresponderende protein.

Answer 21

aflaesning af kodons i mRNA, som bliver genkendt af **anti-kodons** i tRNA igennem antiparallel komplementaer baseparring og hvor en tRNA med en given anti-kodon altid er bundet til en specifik type aminosyre.

Answer 22

**AUG** som binder til tRNA med aminosyre Methionine (MET, M) og hvorefter læserammen er fastlagt (læseramme = opdelingen af RNA sekvens i triplets svarende til kodons).

Answer 23

en teori er at der er ingen mRNA repair i forbindelse med RNA transskription og mRNA splejsning hvilket kan resultere i mRNA med nonsense codons pga fejl og derfor potenielt dannelse af for korte proteiner. Sådanne korte proteiner kan vaere skadelige for cellen og derfor fordel for cellen at hindre de bliver lavet.

Answer 24

normalt er stop codon placeret i det sidste eller naestsidste exon af 3' enden, men i NMD er stop codon fundet tidligere i proteinet, og dermed kan mRNA blive nedbrudt og som konsekvens mindre protein maengde.

Answer 25

- sugar (deoxyribose) - phosphate - nitrogenous base

Answer 26

cysteine and thymine single carbon ring

Answer 27

adenine and guanine double ringed carbon structure

Answer 28

the double helix structure of DNA

Answer 29

backbone composed of sugar and phosphate, while the nitrogenous bases are pointed inward, making DNA basic. ^held together by phosophodiester bonds

Answer 30

1. DNA packed arund histones (140-150bp) 2. forms a nucleosome 3. nucleosomes turn to form solenoid structure (includes about 6 nucleosomes) 4. solenoid organized into chrom. loops

Answer 31

Hydrogen bonds break b/w bases - produces ssDNA complementary base pairing template strand **DNA polymerase** - adds nucleotides to 3' end of the new strand. - Also performs **proofreading**

Answer 32

5'-3' direction

Answer 33

human DNA replication is slow, to speed it up, there are multiple replication origins, which results in multiple seperations of the DNA strands called **replication bubbles**.

Answer 34

added to RNA 5' end during synthesis to prevent degradation. Also helps to indicate the starting position for translation of the mRNA.

Answer 35

termination sequence is reached.

Answer 36

adeninde bases are added to the 3' end of the RNA molecule. - this structure is involved in stabilizing the mRNA molecule so that it is not degraded when it reaches the cytoplasm

Answer 37

Acetylation - acetyl group attached to lysine in histones. Acetylation of histones decreases the histones ability to tightly bind to DNA. Allowing more transcription activity

Answer 38

Acetylation - acetyl group attached to lysine in histones. Acetylation of histones decreases the histones ability to tightly bind to DNA. Allowing more transcription activity

Answer 39

Less transcriptionally active DNA, more condensed, less acetylated,

Answer 40

- methylation of promoter regions - miRNA - 17-27 small RNA molecules that are not translated, but bind to RNA and downregulate it and cause destabilization.

Answer 41

two alpha helices are connected by a short chain of amino acids which constitute the turn. the carboxyl terminal helix is a recognition helix that binds the DNA major groove.

Answer 42

two alpha helices (one short and onr long) are connected by a flexible loop. The loop allows the two helices to fold back and interact with one another. The helices can bind to DNA or to other helix-loop-helix structure

Answer 43

zinc molecules are used to stabilize an amino acid structure (helices, beta sheets,( with binding of the alpha helix to the DNA major groove

Answer 44

two leucine rich alpha helixes are held together by an amino acid side chains. the alpha helices form a Y shaped structure whose side chains bind to the DNA major groove.

Answer 45

side chains extend from the two stranded beta sheets to form contacts with the DNA helix

Answer 46

a type of short RNA sequence bind single specific targets and are used in cancer therapy and some forms of gene therapy

Answer 47

long coding RNA length greater than 200 nucleotides. some are involved in gene regulation. ex: lncRNA encoded by the XIST gene, which inactivates one X chromosome in the genomes of female embryoes.

Answer 48

splicing enzymes are directed to appropriate locations by DNA sequences known as consensus sequences. These are situated adjacent to the exon.

Answer 49

Satellite DNA - clustered together in certain chromosome locations, where they can occur as tandem repeats (beginning of one repeat occurs immediately adjacent to the end of another repeat) Dispersed Repetitive DNA - scattered singly throughout the genome; they do not occur in tandem

Answer 50

mini: - blocks of tandem repeats whose totalt length is much smaller, usually a few thousands bp micro: evens smaller both are useful in forensics

Answer 51

mitosis - nuclear division cytokinesis - cytoplasmic division before a cell can divide, it must duplicate its DNA in the interphase of the cell cycle.

Answer 52

a family of kianses that phosphorylate other regulatory proteins at key stages of the cell cycle. Faulty regulation can lead to cancer.

Answer 53

Prophase - chromosomes become visible - nuclear membrane disappears - spindle fibers form (radiating from to centrioels, located on opposite sides of the cell) Metaphase - chromosomes are most highly condensed - chromosomes located in the equatorial plane, and very easy to see through a microscope Anaphase - centromere of each chromosome splits, allowing sister chromatids to seperate. - Spindle fibers attach to centromere and is pulled to the opposite sides of the cell - now the cell contains 92 seperate chromosomes Telophase - new nuclear membrane around each set of 46 chromosomes. - spindle fibers disappear - chromsomes decondense - cytokinesis - division of cytoplasm completion of telophase = **2 diploid daughter cells, both identical to the original cell**.

Answer 54

Prophase I - chromatin strands coil and condense, causing them to become visible chromosomes - **synapsis**: homologous chromosomes pair up side by side - chromatids of two chromosomes intertwine (bivalent or tetrad) - chiasmata : cross shaped strucutres that mark attachments between the homologous chromosomes. Each chiasma indicates a point at which the homologous chromosomes. **Crossing over**: produces chromosomes that consist of combinations of parts of the original chromsomes. - spindle forms - nuclear membrane disappears Metaphase I - completion of spundle formation and alignment of the bicalents which are still attatched at chiasmata in the equatorial plane Anaphase I - chiasmata disappear - homologous chromosomes are pulled by the spindle fibers towards opposite sides of the cell - centromeres do NOT duplicate and divide so that only half of the original number of chromosomes migrate toward each pole - chrom. migrating toward each pole thus consists of each pair of autosome and one pair of sex chromosomes Telophase I - chrom. reach opposite sides of the cells - new nuclear membrane forms - two daughter cells contain haploid number of chrom and each chrom. has two sister chromatids - cytokinesis ( in females, all cytoplasm goes into one of the daughter cell, while the other becomes a **polar body**)

Answer 55

meiosis I - reduction division stage - two haploid cells are formed from a diploid cell. - these haploid cells are oogonia in females and spermatogonia in men Meiosis II - Equational division - each haploid cell is replicated

Answer 56

Interphase II - no replication Prophase II - chromosomes thicken - nuclear membrane disappears - spindle fibers form Metaphase II - spindle fibers pull the chromosomes into alignment at the equatorial plane Anaphase II - centromere split and each carries a single chromatid toward a pole of the cell. Chromatids have now seperated but because of chiasma formation and crossing over, the newly seperated sister chromatids may not be identical Telophase II - chrom. reach opposite sides of the cell an begin to uncoil. - new nulcear membranes are formed - cytokinesis - females: unequal division again of cytplasm leading to one egg cell and another polar body. - the polar body formed in meiosis I may have undergone division leading to sometimes on egg cell and three polar bodies.

Modul 1 Flashcards

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