Unit 5 Flashcards
Deoxyribonucleic acid (DNA)
A double-stranded polymer of nucleotides (each consisting of a deoxyribose sugar, a phosphate, and four nitrogenous bases) that carries the genetic information of an organism.
Bacteriophage
Any bacteria-infecting virus
Isotope
Différent atoms of the same element containing the same number of protons but a different number of neutrons
Radioisotopes
Unstable isotopes that decay spontaneously by emitting radiation
Deoxyribose sugar
Sugar molecule containing five carbons that has lost the -OH (hydroxyl group) on its 2’ (2 prime) carbon
Phosphate group
Group of four oxygen atoms surrounding a central phosphorus atom found in the backbone of DNA
Nitrogenous base
An alkaline, cyclic molecule containing nitrogen
Nucleotides
Molecules that consist of a five-carbon sugar (deoxyribose or ribose) with a nitrogenous base attached to their 1’ carbon and a phosphate group attached to their 5’ carbon
Antiparallel
Parallel but running in opposite directions; the 5’ end of one strand of DNA aligns with the 3’ end of the other strand in a double helix.
Complementary base pairing
Pairing of the nitrogenous base of one strand of DNA with the nitrogenous base of another strand; adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C).
Glycosyl bond
A bond between a sugar and another organic molecule by way of an intervening nitrogen or oxygen atom
Friedrich Miescher
- Late 1860s
- Isolated nonprotein substance from nucleus of cells; named this substance nuclein
Frederick Griffith
- 1920s
- experimented using mice and two different strains of pneumococcus bacteria (virulent and nonvirulent); observed that when heat-treated virulent pneumococcus was mixed with nonvirulent pneumococcus and was injected into healthy mice dealt resulted
- Discovered the process of transformation
Joachim Hammerling
- 1930s
- experimented using green alga Acetabularia; observed that regeneration of new appendages was driven by the nucleus-containing “foot” of the alga
- hypothesized that hereditary information is stored in the nucleus
Oswald Avery, Maclyn McCarty, and Colin MacLeod
- 1944
- demonstrated that DNA was the transforming principle of pneumococcus bacteria
Erwin Chargaff
- 1949
- discovered that in the DNA of numerous organisms the amount of adenine is equal to the amount of thymine, and the amount of guanine is equal to that of cytosine.
Alfred Hershey and Martha Chase
- 1952
- used radioactively labeled viruses, infected bacterial cells; observed that the infected bacterial cells contained radioactivity originating from DNA of the virus
- suggested that DNA is hereditary material
Rosalind Franklin
- 1953
- produced an X-ray diffraction pattern of DNA that suggested it was in the shape of a double helix
James Watson and Francis Crick
- 1953
- deduced the structure of DNA using information from the work of Chargraff, Franklin, and Maurice Wilkins
Mitosis
Division of the nucleus of a eukaryotic cell into two daughter nuclei with identical sets of chromosomes.
Cytokinesis
Division of cytoplasm and organelles of a cell into two daughter cells.
Template
A single-stranded DNA sequence that acts as the guiding pattern for producing a complementary DNA strand.
Semiconservative
Process of replication in which each DNA molecule is composed of one parent strand and one newly synthesized strand.
DNA helicase
The enzyme that unwinds double-helical DNA by disrupting hydrogen bonds.
anneal
the pairing of complementary strands of DNA through hydrogen bonding
single-stranded binding proteins (SSBs)
a protein that keeps separated strands of DNA apart
DNA gyrase
the bacterial enzyme that relieves the tension produced by the unwihding of DNA during replication
replication fork
the region whers the enzymes replicating a DNA molecule are bound to untwisted, single-stranded DNA
replication bubble
the region where two replication forks are in close proximity to each other, producing a bubble in the replicating
DNA
DNA polymerase III
the enzyme responsible for synthesizing complementary strands of DNA during DNA replication
deoxyribonucleoside
triphosphates
molecules composed of a deoxyribese bonded to three phosphate groups and a nitrogenous base
RNA (ribonucleic acid) primer
a sequence of 10060 RNA bases that is annealed to a region of single-stranded DNA for the purpose of initiating DNA replication
primase
the enzyme that builds
RNA primers
leading strand
the new strand of DNA that is Synthesized continuously during DNA replication
lagging strand
the new strand of DNA that is synthesized in short fragments, which are later joined together
Okazaki fragments
short fragments of DNA that are a result of the synthesis of the lagging strand during DNA replication
DNA polymerase I
an enzyme that removes RNA primers and replaces them with the appropriate deoxyri-bonucleotides during DNA replication
DNA ligase
the enzyme that joins
DNA fragments together by catalyzing the formation of a bond between the 3’ hydroxyl group and a 5’phoshate group on the sugar-phospate backbones
exonuclease
an enzyme that cuts outnucleolides at the end of a DNA strand
genes
a sequence of nucleotides in DNA that performs a specific function such as coding for a particular protein
proteins
complex molecules composed of one or more polypeptide chains made of amino acids and folded into specific three-dimensional shapes that determine protein function
amino acid
the monomer unit of a polypeptide chain that is composed of a carboxylic acid, an amino group, and a side group that differentiates it from other amino acids
transcription
the process in which
DNA is used as a template for the production of complementary messenger RNA molecules
translation
the process by which a ribosome assembles amino acids in a specific sequence to synthesize a specific polypeptide coded by messenger RNA
messenger RNA (mRNA)
the end product of transcription of a gene, mRNA is translated by ribosomes into protein