Chapter 5 The Structure of DNA Flashcards

Question

What is a karyotype?

Answer 1

An ordered display of the of the full set of human chromosomes.

Answer 2

Fluorescent In Situ Hybridization. Used fluorescent probes to detect DNA sequences. Often used to used in human genetics to analyze the chromosomal content of cells and to detect mutational changes in chromosomes. It can detect the deletion of a gene.

Answer 3

It detects the location of a gene on a intact chromosome

Answer 4

It is Latin for "In place"

Answer 5

1. ) Cell arrested in metaphase 2. ) Treated to make them swell 3. ) They are then fixed on to the surface of a slide. This also fixes the chromosomes to the surface of a slide 4. ) Chromosomal DNA is denatured into single stands 5. ) DNA probes are flooded on to the slide. The DNA probes are small pieces of single stranded DNA with a complementary sequence to the gene of interest. 6. ) They hybridize with the gene of interest (They DNA probes are either fluorescently labelled or fluorescent labels are attached to them). 7. ) They are then viewed under a fluorescent microscope and the location of the gene of interest is revealed.

Answer 6

1. ) Cell arrested in metaphase with colchicine 2. ) Treated to make them swell 3. ) They are then fixed on to the surface of a slide. This also fixes the chromosomes to the surface of a slide 4. ) Chromosomal DNA is denatured into single stands 5. ) DNA probes are flooded on to the slide. The DNA probes are small pieces of single stranded DNA with a complementary sequence to the gene of interest. 6. ) They hybridize with the gene of interest (They DNA probes are either fluorescently labelled or fluorescent labels are attached to them). 7. ) They are then viewed under a fluorescent microscope and the location of the gene of interest is revealed.

Answer 7

The DNA of one organism is labeled, then mixed with the unlabeled DNA to be compared against. The mixture is incubated to allow DNA strands to dissociate and renewal forming hybrid double-stranded DNA. Hybridized sequences with a high degree of similarity will bind more firmly, and require more energy to separate them: i.e. they separate when heated at a higher temperature than dissimilar sequences, a process known as "DNA melting". To assess the melting profile of the hybridized DNA, the double-stranded DNA is bound to a column and the mixture is heated in small steps. At each step, the column is washed; sequences that melt become single-stranded and wash off the column. The temperatures at which labeled DNA comes off the column reflects the amount of similarity between sequences (and the self-hybridization sample serves as a control). These results are combined to determine the degree of genetic similarity between organisms.

Answer 8

When centrosomes line up the sister at the center of the center of the cell right before they are to be pulled apart in cell division.

Answer 9

When centrosomes line up the sister at the center of the center of the cell right before they are to be pulled apart in cell division.

Answer 10

The phosphate group on the sugar phosphate backbone

Answer 11

With a 3'sugar or a 5'phosphate group.

Answer 12

2 meters | 5-8 um

Answer 13

1. ) Double helix 2. ) Nucleosome 3. ) Chomatin fiber 4. ) DNA looping 5. ) Chromosome

Answer 14

Consists of DNA and histone proteins. It is the second level of DNA packaging. Sometimes referred to as bears on a string. DNA wraps around it 1.67 times.

Answer 15

They are a major class of proteins that are bound to DNA to form the nucleosome.

Answer 16

H1, H2A, H2B, H3, H4 | They are classified by the ratio of the lysine: arginine amino acid present in the protein

Answer 17

8 histone proteins form the positively charged core around which the negatively charged DNA easily winds. The nucleosome core is made of H2A:H2B pairs (dimers) and two H3:H4 pairs

Answer 18

H1. It connects each core together

Answer 19

Because of the lysine and arginine present.

Answer 20

The 30nm chromatin fiber is made of nucleosomes connected by the H1 protein. It is the third level of DNA packaging.

Answer 21

The forth level of DNA structure. The 30 nm fiber are packaged in to a looping structure that insists of thicker fibers.

Answer 22

50,000-100,000 pairs

Answer 23

Chromatin is packed into chromosomes with contain long strings of gene.

Answer 24

Interphase chromosomes, which are less condensed long threats of DNA because they are so spread out they cannot be seen Metaphase chromosomes, which are more condenses because of this condensation they can be seen.

Answer 25

structure that bind to the mitotic spindle during mitosis and allows for separation. No DNA sequence has been identified for them

Answer 26

region where centromere associated proteins bind

Answer 27

It is an ordered set of the full set of an organism's chromosomes. 23 homologous pairs expect for the the sex chromosome in men.

Answer 28

End of the chromosomes that contains repetitive sequences that allow for chromosomal replication

Answer 29

Euchromatin: A less condensed DNA structure Heterochromatin: A more condenses DNA structure

Answer 30

It allows packaged DNA to be accessible to other proteins

Answer 31

Because it is condenses the genes on heterochromatin are not expressed, therefro it contains few genes. It is found mainly in centromere sand telomeres

Answer 32

Nuclear pore complex (NPC) Small molecules can enter the nucleus without regulation, but large macromolecules such as RNA and proteins requires association with improtin to ender the nucleus and exportin to exit. The number of NPC vary with the cell size and activity roughly 200 in yeast 2000-5000 in a proliferating human cell

Answer 33

It is a basket like structure called the nuclear base

Answer 34

Yes, it requires GTP. Anything under 40 kDa and pass by diffusion.

Answer 35

They have an amino acid tag on the exposed surface of the protein. Generally it is positively charges and made of lysine and arginines. This is called the Nuclear localization signal (NLS). The residues are not necessarily in a row. Sometimes they are together, sometimes they are separated.

Answer 36

That it removed there is nothing else that will sent the macromolecule to the nucleus and if transferred to another cell that doesn't become in the nucleus it will be sent there anyway

Answer 37

cytosolic fibrils extend in the the cytosol, a nuclear basket extends in the the nucleus. It is a complex structure of 30 proteins. It is implanted in the nucleus' double membrane structure. There are gel like fibers at its center, which interact with the phenylalanine on importune beta subunit and those many interactions move it through the pore.

Answer 38

It is recognized by a nuclear import receptor, which directs the newly synthesize protein into a nuclear pore by interacting with the tentacle like fibril that extend from the of the pore. After it is captured, it moves through the gel-like meshwork of nuclear fibrils until entry into the nuclear pore triggers cargo release.

Answer 39

It is in the nucleus. It binds to importin's beta subunit causing it to discharge its cargo. It then powers the importin out of the cell.

Answer 40

It is the nuclear import receptor that brings macromolecules into the nucleus. The alpha part grips the cargo and the beta part has amino acids (phenylalanine) that interact with the gel-like meshwork and guide it through the nuclear pore

Answer 41

1.) Phosphorylation (adding of a negative charge) to residues adjacent to the NLS can prevent it from binding to importin 2.) Conformational changes to the macromolecule with the NLS can prevent it from going towards the nucleus. 3.) Changes in protein protein interaction hiding the NLS For example, if the NLS is covered it cannot bind to importin. 4.) Changes in calcium concentration lead to conformation changes exposing or hiding an NLS.

Answer 42

When a hormone is passed through the membrane, it binds to its receptor and exposes the NLS. The hormone bound receptor then enters the nucleus and then encourages transcription to RNA of of genetic code for male proteins.

Answer 43

a small GTPase. It binds GTP and GDP. Changes shape depending on which it is bound to.

Answer 44

Importing alpha--cargo recognition (detects the NLS) | Importin beta--pore recognition

Answer 45

A short sequence of the 5-6 hydrophobic residues on a protein that target it for export from the cell nucleus to the cytoplasm. It is recognized by and bound by exportin

Answer 46

In the nucleus exporting bind the cargo and RanGTP and diffuses through the cytoplasm. Once in the cytoplasm, cleaving the RanGTP to RanGDP releases the cargo.

Answer 47

restrcition of expression of genes placed near heterochromatin

Answer 48

The activity of a gene depends on relative location to heterchromatin

Answer 49

An individual chromosome composition

Answer 50

Through histone modification because histone control the packaging and modification of DNA

Answer 51

An N-tail. The amino acids on the tail can be covalently modified to the effect the condensation of the DNA

Answer 52

Acetylation and methylation

Answer 53

It removes a positive charge from the histone and loosens chromatin structure

Answer 54

It tighten chromatin structure and prevent acetylation

Answer 55

GTP is 10x concentration in the nucleus. GDP is 10x concentration cytoplasm This is controlled by proteins on either side the regulate the making to the structure.

Answer 56

The Rev protein somehow coopts the importin/exportin system to favor the replication and transport out the cell code to build more virus

Answer 57

Many cancers occur because of mutation in the NLS. Moreover, the cell may have the right protein, but if it doesn't get to its target (the nucleus) it cannot fulfill its function.