Nucleic Acids

Question 1

central dogma of molecular biology

Answer 1

DNA transcription to RNA and its translation to protein

Question 2

DNA

Answer 2

double-stranded chains of deoxyribonucleotides that reside in the nucleus

Question 3

RNA

Answer 3

single-strande d chains of ribonucleotides that are transcribed in the nucleus and translated in cytosol

Question 4

proteins

Answer 4

chains of amino cytosol but involved in all different areas of the cell

Question 5

what are DNA and RNA the source of?

Answer 5

genetic info. in humans

Question 6

DNA in eukaryotes

Answer 6

it is present in the nuclei of their cells (small amount contained in mitchondria)

Question 7

DNA in prokaryotes

Answer 7

circular DNA that is not separate from the rest of the cell contents

Question 8

what do viruses do?

Answer 8

utilize DNA or RNA for their genetic info. but require other host cells whose replication machinery they hijack in order to multiply; can infect eukaryotic organisms and prokaryotes as well

Question 9

what are viruses that infect bacteria called?

Answer 9

bacteriophages

Question 10

plasmids

Answer 10

circular DNA molecules that can enter bacterial cells and replicate independently of the genomic DNA; not infectious but are important since they can confer antibiotic resistance to bacteria

Question 11

DNA bases

Answer 11

adenine, guanine, cytosine, thymine; they are nitrogenous

Question 12

which bases are purines?

Answer 12

adenine and guanine

Question 13

which bases are pyrimidines?

Answer 13

thymine and cytosine

Question 14

what are the DNA base pairs?

Answer 14

A binds to T, G to C

Question 15

DNA sugars

Answer 15

at the second carbon, will have an H instead of an OH hence “deoxy”

Question 16

RNA sugars

Answer 16

ribose sugar; at the second carbon, will have an OH

Question 17

what is a sugar bonded to a base called?

Answer 17

a nucleoside

Question 18

once a phosphate is added to a nucleoside, it is called a…

Answer 18

nucleotide

Question 19

at which end does one phosphate attach to another ?

Answer 19

at 5’

Question 20

what does the DNA backbone consist of?

Answer 20

sugar and phosphate

Question 21

at which carbon is the attachment point for the phosphate?

Answer 21

at the 3’ carbon

Question 22

what type of bond links nucleotides?

Answer 22

phosphodiester bonds

Question 23

how many hydrogen bonds are between A and T?

Answer 23

2 hydrogen bonds

Question 24

how many hydrogen bonds are between C and G?

Answer 24

3 hydrogen bonds

Question 25

what do the hydrogen bonds between the nitrogenous bases do?

Answer 25

stabilize DNA structure but are weak enough to allow separation of helices for replication + transcription

Question 26

DNA replication

Answer 26

process in which DNA makes a duplicate copy of itself in semi-conservative manner; each strand provides the template for a new strand and attaches to that new strand to create helices

Question 27

antiparallel nature of DNA

Answer 27

the strands run in opposite directions (5’ to 3’ and then 3’ to 5’); each strand can serve as a template for the strand

Question 28

complementarity

Answer 28

a pyrimidine is always H-bonded to the same purine

Question 29

sense strand

Answer 29

the strand of DNA that runs 5’ to 3’ and contains the genetic code for a protein

Question 30

antisense strand

Answer 30

the strand of DNA that runs 3’ to 5’ and acts as a template strand during transcription

Question 31

what charge does DNA carry?

Answer 31

negative; two oxygen molecules of the phosphate group form the phosphodiester bond, the free OH loses its L at physiological pH (allows binding/association of proteins or other molecules in major or minor grooves)

Question 32

DNA packaging

Answer 32

eukaryotic DNA wraps around histones to form a solenoid structure (nucleosomes) that packs DNA tightly inside the nucleus

Question 33

what do histones consist of?

Answer 33

many arginines and lysines (+vely charged)

Question 34

chromosomes

Answer 34

threadlike structures made of DNA molecules that contain the genes

Question 35

genome

Answer 35

total of all DNA in the cell

Question 36

haploid

Answer 36

an organism or cell having only one complete set of chromosomes (23 in humans)

Question 37

diploid cell

Answer 37

a cell containing two sets of chromosomes (2n), one set inherited from each parent (46 in humans)

Question 38

gene

Answer 38

sequence of DNA (plus its regulatory regions) that code for a protein or RNA molecule

Question 39

homologous chromosomes

Answer 39

chromosomes that have the same sequence of genes and the same structure

Question 40

alleles

Answer 40

different versions of a gene

Question 41

single nucleotide polymorphism

Answer 41

variation in a DNA sequence occurring when a single nucleotide in a genome is altered

Question 42

what is the differing base in RNA? which base does it replace?

Answer 42

uracil (U) replaces thymine

Question 43

Types of RNA

Answer 43

mRNA, tRNA, rRNA

Question 44

messenger RNA

Answer 44

RNA molecule that carries copies of instructions for the assembly of amino acids into proteins from DNA; exported into cytoplasm to direct protein synthesis (transcribed from antisense strand)

Question 45

Ribosomal RNA

Answer 45

type of RNA that associates with proteins to form ribosomes; subunits differ between prokaryotes and eukaryotes

Question 46

transfer RNA

Answer 46

RNA in the cytoplasm that carries an amino acid to the ribosome and adds it to the growing protein chain

Question 47

anticodon

Answer 47

a sequence of three nucleotides complementary to the mRNA sequence so it can be “read” and the correct a.a. can be added to the polypeptide chain

Question 48

reverse transcriptase

Answer 48

a polymerase that catalyzes the formation of DNA using RNA as a template; some viruses insert this into a host’s chromosome and hijack its transcription and translation machinery (permanently incorporated into host DNA)