chapter four: DNA and RNA & genes and their actions

Question 1

Where are genes kept?

Answer 1

DNA

Question 2

How many molecules of DNA do most human cells have?

Answer 2

46

Question 3

What is DNA and other nucleic acids composed of?

Answer 3

nucleotides

Question 4

What does a nucleotide consist of?

Answer 4

sugar
a phosphate group
nitrogenous base

Question 5

What is the basis of the genetic code?

Answer 5

nitrogenous bases

Question 6

What pyrimidines?

Answer 6

cytosine
thymine
uracil

Question 7

What are purines?

Answer 7

adenine
guanine

Question 8

What is the commonly described structure of DNA?

Answer 8

double helix

Question 9

What is each sidepiece of the structure of DNA composed of?

Answer 9

phosphate groups alternating with the sugar deoxyribose

Question 10

What holds the two backbones of DNA together?

Answer 10

hydrogen bonds

Question 11

What is the law of complementary base pairing?

Answer 11

one strand governs the base sequence of the other strand

Question 12

What does adenine pair with?

Answer 12

thymine

Question 13

What does guanine pair with?

Answer 13

cytosine

Question 14

What does the law of complementary base pairing allow for?

Answer 14

prediction of the sequence of one strand if the other is unknown

Question 15

What is the essential function of DNA?

Answer 15

to carry instructions, called genes, to synthesize proteins

Question 16

What is chromatin?

Answer 16

filamentous material in the nucleus, composed of DNA and associated proteins

Question 17

What does the chromatin occur as in most cells?

Answer 17

46 long filaments called chromosomes

Question 18

What are chromosomes?

Answer 18

a complex of DNA and protein carrying the genetic material of a cell’s nucleus

Question 19

How is DNA able to be packed into the nucleus so it does not become tangled, broken, and damaged?

Answer 19

it is extensively coiled and supercoiled

Question 20

What does DNA wind around and what does it form?

Answer 20

winds around histone proteins to form core particles

Question 21

What is a chromosome territory?

Answer 21

a spheroidal region of the nucleus where a chromosome is packed into

Question 22

What is the chromosome territory permeated with?

Answer 22

channels to allow regulatory chemicals to have access to the genes

Question 23

What are sister chromatids?

Answer 23

two identical chromatids that are formed by replication

Question 24

Where are sister chromatids joined at?

Answer 24

centromere

Question 25

What is a kinetochore?

Answer 25

attachment point for the spindle microtubules to pull the chromosomes apart

Question 26

What are the three types of RNA?

Answer 26

mRNA rRNA tRNA

Question 27

True or false: RNA is much smaller than DNA.

Answer 27

true

Question 28

True or false: RNA is a double helix.

Answer 28

false: RNA is a single nucleotide chain

Question 29

What is the sugar in RNA?

Answer 29

ribose

Question 30

What base pair replaces thymine in RNA?

Answer 30

uracil

Question 31

What is the function of RNA?

Answer 31

interpret the code in DNA and carries out its instructions directs the synthesis of proteins

Question 32

Where is the site of RNA action?

Answer 32

cytoplasm

Question 33

Where is the site of action of DNA?

Answer 33

nucleus

Question 34

What is a gene?

Answer 34

an information-containing segment of DNA that codes for the production of a molecule of RNA

Question 35

What is the amino acid sequence of a protein determined by?

Answer 35

the nucleotide sequence in the DNA

Question 36

What is a genome?

Answer 36

all the genes of one individual

Question 37

What accounts for all human genetic variation?

Answer 37

single-nucleotide polymorphisms

Question 38

What is the genetic code?

Answer 38

a system that enables the 4 nucleotides to code for the amino acid sequences of all proteins

Question 39

What is the genetic code expressed in?

Answer 39

terms of codons

Question 40

What is a base triplet?

Answer 40

a sequence of 3 DNA nucleotides that stands for 1 amino acid (ex. CCT)

Question 41

What is a codon?

Answer 41

a 3 base sequence in mRNA (ex. DNA = CCT -> RNA = GGA)

Question 42

What does the genetic code in DNA specify?

Answer 42

which proteins a cell can make

Question 43

What happens when a gene is activated?

Answer 43

mRNA is made and migrates to the cytoplasm where it is "read" by a ribosome serves to make a particular protein

Question 44

What is the flow of protein synthesis?

Answer 44

DNA -> mRNA -> protein

Question 45

What is transcription?

Answer 45

the process where DNA is copied into RNA

Question 46

What is RNA polymerase?

Answer 46

enzyme that binds to the DNA and assembles the RNA

Question 47

What is the RNA produced by transcription called?

Answer 47

pre-mRNA

Question 48

What does pre-mRNA contain?

Answer 48

exons and introns

Question 49

What are exons?

Answer 49

the segment that will be translated into a protein

Question 50

What are introns?

Answer 50

segments that are removed before translation

Question 51

What is alternative splicing?

Answer 51

one gene can code for more than one protein

Question 52

What is translation?

Answer 52

the process in which a ribosome reads an mRNA molecule and synthesizes the protein specified by its genetic code

Question 53

What is translation?

Answer 53

the process in which a ribosome reads an mRNA molecule and synthesizes the protein specified by its genetic code

Question 54

What particles carry out translation?

Answer 54

mRNA tRNA ribosomes

Question 55

What carries the genetic code from the nucleus to the cytoplasm?

Answer 55

mRNA

Question 56

What is a protein cap?

Answer 56

a "passport" acquired by mRNA that permits it to pass through a nuclear pore into the cytosol

Question 57

The mRNA protein cap also acts as a recognition site. What does that mean?

Answer 57

tells a ribosome where to begin translation

Question 58

What is tRNA?

Answer 58

bind a free amino acid in the cytosol and deliver it to the ribosome to be added to a growing protein chain

Question 59

What is an anticodon?

Answer 59

one loop of a tRNA molecule that is a series of 3 nucleotides complementary to a specific codon of mRNA (ex. codon = AUG; anticodon = UAC)

Question 60

What is the amino acid-accepting end of tRNA?

Answer 60

binds to a specific amino acid corresponding to that codon

Question 61

What are ribosomes composed of?

Answer 61

enzymes and rRNA

Question 62

What is the purpose of the three pockets on ribosomes?

Answer 62

serve as binding sites for tRNA

Question 63

What is the A site?

Answer 63

accepts new amino acids

Question 64

What is the P site?

Answer 64

carries the growing protein

Question 65

What is the E site?

Answer 65

exit

Question 66

What are the three steps of translation?

Answer 66

initiation elongation termination

Question 67

What is a polyribosome?

Answer 67

cluster of ribosomes all translating the same mRNA

Question 68

What is a chaperone protein?

Answer 68

a protein that guides a new protein strand into its proper configuration and prevents improper associations between different proteins

Question 69

If a protein is going to be used in the cytosol, where is it likely to be made?

Answer 69

free ribosomes in the cytosol

Question 70

If a protein is going to be packaged into a lysosome or secreted from the cell, where is it likely to be made?

Answer 70

on the rough ER

Question 71

What are the six steps of protein processing and secretion?

Answer 71

1. proteins are formed by ribosomes on rough ER 2. proteins are packaged into transport vesicles, which bud off from the ER 3. transport vesicles fuse into clusters to form a new cis cistern 4. Golgi complex modifies protein structure 5. trans cistern breaks up into vesicles 6. secretory vesicles release protein by exocytosis

Question 72

What are regulatory proteins?

Answer 72

proteins that can turn gene transcription on or off

Question 72

What are regulatory proteins?

Answer 72

proteins that can turn gene transcription on or off

Question 73

How does the cell synthesize glycogen, fat, steroids, phospholipids, pigments, and many other compounds since there are no genes for these cell products?

Answer 73

these products are produced by enzymatic reactions, and enzymes are proteins encoded by genes