Mcat Biochemistry Chapter 6

Front 1

nucleosides

Back 1

five-carbon sugar bonded to nitrogenous base

Front 2

nucleotides

Back 2

nucleoside (five-carbon sugar & nitrogenous base) with one to three phosphate groups added

A, T, C, G, U

Front 3

direction to read DNA

Back 3

5' - 3'

Front 4

Purines

Back 4

A and G (2 rings)

Front 5

pyrimidines

Back 5

C, U, T (1 ring)

Front 6

Huckel's rule

Back 6

determines number of electrons in purines and pyrimidines

Front 7

Chargaff's rules

Back 7

purines and pyrimidines are equal in number in a DNA molecule, A=T, C=G

Front 8

most DNA is shaped as:

Back 8

B-DNA (right-hand helix)

Front 9

what would cause DNA to change from its helical shape

Back 9

high concentrations of GC or salt can change B-DNA to Z-DNA (zigzag shape)

Front 10

reannealed

Back 10

DNA strands brought back together

removal of heat, alkaline pH, or chemicals like formaldehyde or urea

Front 11

denatured

Back 11

DNA strands are pulled apart

heat, alkaline pH, chemicals like formaldehyde and urea

Front 12

histone proteins

Back 12

what DNA wraps around (H2A, H2B, H3, H4)

Front 13

nucleosomes

Back 13

DNA wound around histone proteins

Front 14

stabilization histone protein

Back 14

H1

Front 15

chromatin

Back 15

DNA and associated histones. resides in nucleus

Front 16

heterochromatin

Back 16

dense, transcriptionally silent DNA that appears dark under light microscopy

Front 17

euchromatin

Back 17

less dense, transcriptionally active DNA that appears light under light microscopy

Front 18

telomeres

Back 18

ends of chromosomes. high GC content to prevent unraveling of DNA. partially shortened during replication, which may be partially reversed by telomerase

Front 19

centromeres

Back 19

middle of chromosomes, hold sister chromatids together until separated during anaphase.

high GC content to maintain strong bond between chromatids

Front 20

replisome (replication complex)

Back 20

set of specialized proteins that assist the DNA polymerases

Front 21

helicases

Back 21

unwind DNA at an origin of replication

Front 22

replication fork

Back 22

on either side of an origin of replication, after unravelling

Front 23

origin of replication

Back 23

where DNA unravels from. 1 in prokaryotes, many in eukaryotes

Front 24

single-stranded DNA-binding proteins

Back 24

keep unwound strands of DNA from reannealing or being degraded during replication

Front 25

supercoiling

Back 25

causes torsional strain on DNA molecule

Front 26

DNA topoisomerases

Back 26

release torsional strain caused by supercoiling by making nicks in the DNA molecule

Front 27

primase

Back 27

small RNA primer that allows synthesis of end nucleotides (cannot be synthesized without adjacent nucleotide to hook on to)

Front 28

DNA polymerase II

Back 28

prokaryotes, reads template DNA 3' to 5', synthesize strand 5' to 3'

Front 29

DNA polymerase alpha, delta, epsilon

Back 29

eukaryotes, reads template DNA 3' to 5', synthesize strand 5' to 3'

Front 30

leading strand

Back 30

replicated in the direction of unraveling, requires only one primer

Front 31

lagging strand

Back 31

replicated from fork to end (away from the unraveling molecule), synthesized in segments (okazaki fragments) with multiple primers

Front 32

okazaki fragments

Back 32

sections formed during replication of the lagging strand

Front 33

DNA polymerase I

Back 33

prokaryotes, removes primers and fills in with DNA

Front 34

RNase H

Back 34

eukaryotes, removes primers

Front 35

DNA polymerase delta

Back 35

prokaryotes, fills in primer areas with DNA

Front 36

DNA ligase

Back 36

fuses DNA strands together to create one complete molecule

Front 37

ongocenes

Back 37

develop from mutations of proto-oncogenes, promote cell cycling. may lead to cancer

Front 38

proto-oncogenes

Back 38

code for proteins that stimulate cell division, prevent cell differentiation or regulate apoptosis

Front 39

tumor suppressor genes

Back 39

code for proteins that reduce cell cycling or promote DNA repair

Front 40

Nucleotide excision repair

Back 40

fixes helix-deforming lesions of DNA via cut-and-patch process that requires an excision endonuclease

Front 41

base excision repair

Back 41

fixes nondeforming lesions of the DNA helix by removing the base, leaving an apurinic/apyrimidine site

Front 42

AP endonuclease

Back 42

removes damaged sequence, which can be filled in with correct bases

Front 43

recombinant DNA

Back 43

DNA composed of nucleotides from two different sources

Front 44

DNA cloning

Back 44

introduces fragment of DNA into vector plasmid

Front 45

restriction enzyme (endonuclease)

Back 45

cuts both plasmid and fragment, leaving them with sticky ends

Front 46

Genomic Libraries

Back 46

large fragments of DNA, including both coding and noncoding regions of the genome. cannot be used to make recombinant proteins or for gene therapy

Front 47

cDNA libraries (expression libraries)

Back 47

contain smaller fragments of DNA, only include exons of genes expressed by the sample tissue. can be used to make recombinant proteins or for gene therapy

Front 48

hybridization

Back 48

joining of complementary base pair sequences

Front 49

polymerase chain reaction (PCR)

Back 49

automated process by which millions of copies of DNA sequence can be created from a very small sample by hybridization

Front 50

southern blotting

Back 50

used to detect the presence and quantity of various DNA strands in a sample

Front 51

gene therapy

Back 51

method of curing genetic deficiencies by introducing a functional gene with a viral vector

Front 52

knockout mice

Back 52

created by deleting a gene of interest

Front 53

transgenic mice

Back 53

created by integrating gene of interest into germ line or embryonic stem cells of developing mouse