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48 terms

Biology Chapter 12

Does not include section 12.5
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Frederick Griffith
British scientist, 1928-trying to learn about pneumonia, through experiments with mice and two different strains of bacteria discovered process of transformation
Griffith's experiments
Injected mice with disease-causing strain (smooth colonies), mice died. Injected mice with harmless bacteria (rough colonies), mice lived. Injected mice with heat-killed, disease-causing strain, mice lived. Mixed heat-killed, disease causing, and harmless bacteria, mice died. Led to discovery of transformation.
transformation
process in which one strain of bacteria is changed by a gene or genes from another strain of bacteria
Oswald Avery
Experimented with heat-killed bacteria, treating it with enzymes to destroy proteins, lipids, carbohydrates, etc. Transformation only stopped after DNA was destroyed, which meant that DNA stores and transmits genetic info from one generation to the next.
bacteriophage
virus that infects bacteria, composed of DNA or RNA core and a protein coat
Hershey-Chase experiment
Wanted to find out if genes were made of protein or DNA. Using bacteriophage, made DNA radioactive (with phosphorus), made protein radioactive (with sulfur). Found phosphorus in bacterium infected by bacteriophage, meaning that DNA was the genetic material.
nucleotide
unit of DNA (and RNA), made of 5-carbon sugar (deoxyribose in DNA, ribose for RNA), a phosphate group, and a nitrogenous base
purines
group of compounds including the nitrogenous bases adenine and guanine, contain two rings
pyrimidines
group of compounds including the nitrogenous bases cytosine and thymine, contain one ring
Chargaff's rules
the observation that the percentage of guanine and cytosine bases are almost equal in any sample of DNA, same is true for adenine and thymine
Rosalind Franklin
studied the DNA molecule using a technique called X-ray diffraction, showed that DNA has two strands
James Watson and Francis Crick
1953- developed the double-helix (two strands wound around each other) model of the structure of DNA, strands held together by hydrogen bonds
base-pairing
principle that bonds in DNA can form only between adenine and thymine and between guanine and cytosine
chromatin
granular material visible within the nucleus; consists of DNA tightly coiled around proteins
histone
protein molecule around which DNA is tightly coiled in chromatin
nucleosome
beadlike structure formed by DNA and histone molecules
replication fork
the site where separation and DNA replication occur
replication
copying process by which by which a cell duplicates its DNA
DNA polymerase
enzyme involved in DNA replication that joins individual nucleotides to produce a DNA molecule
gene
sequence of DNA that codes for a protein and thus determines a trait
messenger RNA (mRNA)
RNA molecule that carries copies of instructions for the assembly of amino acids into proteins from DNA to the rest of the cell
ribosomal RNA (rRNA)
type of RNA that makes up the major part of ribosomes
transfer RNA (tRNA)
type of RNA molecule that transfers amino acids to ribosomes during protein synthesis
transcription
process in which part of the nucleotide sequence of DNA is copied into a complementary sequence in RNA
RNA polymerase
enzyme similar to DNA polymerase that binds to DNA and separates the DNA strands during transcription
promoter
region of DNA that indicates to an enzyme where to bind to make RNA
intron
sequence of DNA that is not involved in coding for a protein
exon
expressed sequence of DNA; codes for a protein
polypeptide
a long chain of amino acids
genetic code
the rule that describes how a sequence of nucleotides, read in groups of three consecutive nucleotides that correspond to specific amino acids, specifies the amino acid sequence of a protein
RNA
single-stranded nucleic acid, consists of a long chain of nucleotides (5-carbon sugar ribose, a phosphate group, and a nitrogenous base), contains uracil instead of thymine
codon
three-nucleotide sequence on a messenger RNA that codes for a single amino acid
translation
decoding of a mRNA message into a polypeptide chain
anticodon
group of three bases on a tRNA molecule that are complementary to an mRNA codon
AUG
start codon
mutation
change in a DNA sequence that affects genetic information
point mutation
gene mutation involving changes in one or a few nucleotides (such as substitutions, insertions, and deletions)
frameshift mutation
mutation that shifts the "reading" frame of the genetic message by inserting or deleting a nucleotide
gene mutations
mutations that produce changes in a single gene
chromosomal mutations
mutations that produce changes in whole chromosomes
substitution
type of gene mutation in which one base is changed to another
insertion
type of gene mutation in which one base is inserted in the DNA sequences
deletion
type of gene mutation in which a base is removed from the DNA sequence
deletion
type of chromosomal mutation in which all or part of a chromosome is lost
duplication
type of chromosomal mutation that produces extra copies of parts of a chromosome
inversion
type of chromosomal mutation that reverses the direction of parts of chromosomes
translocation
type of chromosomal mutation in which part of one chromosome breaks off and attaches to another
polyploidy
condition in which an organism has extra sets of chromosomes