Week 1, Lecture 2: Structure of Nucleic Acids

Question 1

What are the Monomeric Units of Nucleic acids, DNA and RNA?

Answer 1

Nucleotides

Question 2

Nucleotides consist of what ?. How are they linked?

Answer 2

nitrogenous base, a five-carbon sugar, and a phosphate….linked by phosphodiester bonds between the 3 -sugar of one nucleotide and the 5 -sugar of the next nucleotide

Question 3

DNA contains the sugar ____? RNA contains ?

Answer 3

2 -deoxyribose; ribose

Question 4

DNA and RNA contain the purine bases

Answer 4

adenine (A) and guanine (G)

Question 5

DNA contains the pyrimidine bases ?

Answer 5

cytosine (C) and thymine (T)

Question 6

RNA contains the pyrimidine bases ?

Answer 6

C and uracil (U)

Question 7

transcription of a gene generates ?

Answer 7

single-stranded RNA

Question 8

the three major types of RNA?

Answer 8

are messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA)

Question 9

What RNAs are required for protein sythesis?

Answer 9

rRNA and tRNA

Question 10

rRNA is complexed with proteins to form ribonucleoprotein particles called? what does this bind?

Answer 10

ribosomes, which bind mRNA and tRNAs during translation

Question 11

What does tRNA contain and where does it bind?

Answer 11

anticodon that binds to a complementary codon on mRNA, ensuring insertion of the correct amino acid into the protein being synthesized

Question 12

DNA is complexed with proteins called ?

Answer 12

histones to form nucleosomes that are further condensed into wound chromatin

Question 13

where is DNA found in the Eukaryote?

Answer 13

nucleus and mitochondria

Question 14

nucleosides lack …?

Answer 14

inorganic phosphates of nucleotides

Question 15

deoxyribonucleotides are abbreviated?

Answer 15

dNMP, dNDP

Question 16

what is the backbone of DNA made of?

Answer 16

sugar-phosphate backbone, created by phosphodiester bonds

Question 17

what charge does DNA have? how does this help?

Answer 17

negative die to oxygen. aids in the binding of specific proteins.

Question 18

DNA has three conformations?

Answer 18

B-DNA (right-handed helix) , A-DNA (right-handed helix), Z-DNA (left-handed helix)

Question 19

found in DNA-RNA hybrids and is more compact than B-DNA?

Answer 19

A-DNA

Question 20

DNA conformation that is formed briefly during transcription?

Answer 20

Z-DNA

Question 21

the genome is all of an organism’s ??

Answer 21

DNA (nuclear and mitochondrial)

Question 22

the nuclear genome of a human haploid cell (sperm or egg) contains # of chromosomes?

Answer 22

23

Question 23

all mitotic progeny of the diploid zygote have a homologous pair of ….?

Answer 23

22 autosomes and one pair of sex chromosomes (male = X,Y; female = X,X) for a total of 46 chromosomes in a single diploid cell

Question 24

the display of the 46 human chromosomes is called ?

Answer 24

Karyotype

Question 25

How can chromosomes be distinguished?

Answer 25

size, staining patterns, and FISH color

Question 26

each DNA molecule that forms a linear chromosome must contain what?

Answer 26

a centromere, two telomeres (ends) and a replication origin

Question 27

Ex. what is this event: a piece of chromosome 4 that had become attached to chromosome 12 through an abnormal recombination event.

Answer 27

chromosomal translocation

Question 28

what does FISH stand for and when is it used?

Answer 28

This technique is called spectral karyotyping and it is a form of of fluorescent in situ hybridization (FISH).

Question 29

The banding patterns of human chromosomes are made by what stain?

Answer 29

Giemsa stain, then light microscope.

Question 30

specific location on a chromosome/

Answer 30

genetic locus

Question 31

alternate gene versions are called?

Answer 31

alleles, two for each gene, one obtained maternally and one paternally

Question 32

if the alleles functionally differ then the gene is called what?

Answer 32

heterozyous

Question 33

a correlation exists between the complexity of an organism and the number of what?

Answer 33

genes in its genome

Question 34

two species have essentially the same set of genes, and that in many cases the genes are found in the same order (mouse and human)? what is this called?

Answer 34

conserved synteny

Question 35

Mobile genetic elements in our genome?

Answer 35

LINES, SINES, retroviral-like elements, and DNA-only transposons

Question 36

short nucleotide sequences that are repeated for long stretches?

Answer 36

Simple sequence repeats

Question 37

large blocks of the genome (100K -200k) that are present at two or more locations in the genome?

Answer 37

Segmental suplications

Question 38

describe Prokaryote DNA? how is it packaged?

Answer 38

single circular chromosome of double-stranded DNA, DNA is supercoiled and attached to an RNA-protein core

Question 39

histones that contain large amounts what AA's?

Answer 39

histones that contain large amounts of arginine and lysine

Question 40

further compaction of chromatin occurs as the strings of nucleosomes wind into helical, tubular coils called?

Answer 40

solenoids

Question 41

this higher order chromatin structure is mediated by ?

Answer 41

H1 histones, but also, especially by the “tails” of the core histones

Question 42

each of the core histones has what?

Answer 42

long N-terminal amino acid “tail” which extends out from the core

Question 43

How are the tails of histones modified?

Answer 43

acetylation of lysines( added by HATs) (removed by HDACs), methylation of lysines and phosphorylation of serines

Question 44

what is the critical role of histone acetylation?

Answer 44

destabilizing chromatin structure , removing positive charge from lysine

Question 45

chromatin that is loose or “open” for transcription and replication is called ?

Answer 45

euchromatin

Question 46

chromatin that is most highly condensed, and thus closed to processes such as transcription is called ?

Answer 46

heterochromatin

Question 47

acetylation of tail histones is associated with ? de-acetylation is associated with?

Answer 47

euchromatin, heterochromatin

Question 48

What is often upregulated in cancer cells? what does this lead to ?

Answer 48

HDACs, to silencing of expression of tumor suppressor genes (such as p53

Question 49

how do ; uracil & thymine differ?

Answer 49

the presence of a methyl group in thymine at position 5 of the ring

Question 50

What is it called:RNAs can also act as enzymes ?

Answer 50

ribozymes

Question 51

mRNA processing?

Answer 51

introns, poly-a-tail and cap

Question 52

where is mRNA processed?

Answer 52

nucleus

Question 53

what are the subunits in prokaryotyic ribosomes? Eukaryotic?

Answer 53

Prokaryotic ribosomes have 50S and 30S subunits and eukaryotic ribosomes have 60S and 40S subunits

Question 54

RNA molecules that carry amino acids to ribosomes and ensure they are incorporated into the correct positions in the polypeptide chain are what?

Answer 54

tRNA

Question 55

pairing of three bases in the tRNA with mRNA are what?

Answer 55

anti-codons and codons

Question 56

serve as primers for DNA replication?

Answer 56

oligonucleotides

Question 57

what are the key functions of miRNAs?

Answer 57

development, cell differentiation, regulation of the cell cycle & apoptosis. regulate mRNA degradation, translation, chromatin condensation

Question 58

What happens when microRNAs are mutated?

Answer 58

can act as either an oncogene or tumor suppressor gene in human cancers