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Reference Guide

College Genetics - Reference Guides

4 pages23 viewsFall 2015

Department
ANAT - Anatomy
Course Code
ANAT 14
Professor
All
Chapter
Permachart

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GENETIC BASICS
Genetics is concerned with heredity and variation
• All living things are products of both nature and nurture;
the heredity unit (gene) provides an organism with its
nature (that is, biological potential and limitations), while
environment provides nurture components
Interaction of nature and nurture provides organisms with
distinct anatomical, physiological, biochemical, and
behavioral characteristics
• Genes reside in a long molecule called deoxyribonucleic
acid (DNA); along with histones, DNA forms nucleosomes
that organize into structures with distinctive staining
properties called chromosomes found in cell’s nucleus
College Genetics
College Genetics
ISOTOPE DATA
Curie (Ci): Unit used to express activity of radioactive substance
• 1 Ci = 1000 mCi = 3.7 ¥1010disintegrations/ second
• 1 becquerel = 1 disintegration/second = 2.7 ¥10-8mCi
• 1 mCi = 3.7 ¥107becquerels
ANALOGY
Earth Cell
Continent Cell nucleus
State Chromosomes
City Chromosomal DNA
Address Gene segment
Isotope Particle Half-life
Emitted
14Cb5.73 years
3Hb12.3 years
125Ig60 days
32Pb14.2 days
33Pb25 days
DNA
Human
metaphase
chromosome
146 base-pairs per
nucleosome core
50
110
13/4 turns to DNA
1 3/4 turns of
the supercoil of
DNA
8 to 114
nucleotide
pairs per
linker
Nucleosome fiber
(extended structure)
DNA deoxyribonucleic acid
34
3.4
10
DNA
GENETIC CODE
Terminal signal:
UAA (Ochre)
UGA (Opal)
UAG (Amber)
Initiators:
• AUG: Met
• GUG: Val (Met)
Properties of DNA:
Stable molecule
• Capable of
self-replication
UUU UCU UAU UGU
UUC UCC UAC UGC
UUA UCA UAA UGA
UUG UCG UAG UGG
CUU CCU CAU CGU
CUC CCC CAC CGC
CUA CCA CAA CGA
CUG CCG CAG CGG
AUU ACU AAU AGU
AUC ACC AAC AGC
AUA ACA AAA AGA
AUG ACG AAG AGG
GUU GCU GAU GGU
GUC GCC GAC GGC
GUA GUA GAA GGA
GUG GCG GAG GGG
First (5’) Letter
serine
proline
threonine
alanine
tyrosine
Ochre (terminator)
Amber (terminator)
histidine
glutamine
asparagine
lysine
aspartate
glutamate
leucine
leucine
phenylalanine
isoleucine
methionine
(initiator)
valine
(initiator)
}
}
}
}
}
}
}
}
}
}
}
}
}
}
}
}
}
}
}
}
}
cysteine
Opal (terminator)
tryptophan
arginine
serine
arginine
glycine
U
C
A
G
UC A G
Third (3’) Letter
UNITS OF MASS
• Molecular weight (mw) is measured in daltons;
1 dalton=mass of hydrogen molecule =
3.32 ¥10-24 g
• Average molecular weight of 1 nucleotide pair ~
66 daltons
• DNA units = kilobase (kb) =1 ¥103bases
• 1.0 kb DNA = coding capacity for 333 amino acids
~37,000 dalton proteins
• 10,000 dalton proteins ~270 base pair (bp) DNA
• 50,000 dalton proteins ~1.35 kilobase (kb) DNA
• MW of a double-stranded DNA molecule =
(number of base pairs) ¥(660 daltons/ base pair)
• Moles of a double-stranded DNA molecule =
2 ¥(grams of DNA)/(MW daltons)
NUCLEIC ACID DATA
MEASURING DISTANCE
• Genetic distances are
expressed in either kb, mb,
or cM (centimorgans)
• 1 cM equals one megabase
(mb) of DNA
• Loci that is 1 cM apart shows
1% recombination
Lengths
• 1 angstrom (Å) ~diameter of
H nucleus = 0.1 nm
• 1 nanometer (nm) = 10 Å =
10-6 mm
• 1 micron/ micrometer (mm) =
10-3 mm
• 1 mm = 1000 mm
POPULAT I O N G E N E T I C S ( H A R D Y-WEINBERG L AW)
• The population is infinitely large and mates at
random
• No selection is operative; therefore, there is
no differential mortality nor differential
reproduction
• The population is closed; no immigration or
emigration
• No mutations from one allelic state to
another; meiosis is normal so chance is only
factor operative in gametogenesis
Second Letter
• 1 mg of 1000 bp DNA = 1.52 pmol =
9.1 ¥1011 molecules
• 1 mg of pBR322 DNA (4361 bp) = 0.35 pmol
= 2.1 ¥1011 molecules
• 1 mg of l DNA (48502 bp) = 0.03 pmol =
1.8 ¥1010 molecules
• 1 pmol of 1000 bp DNA = 0.66 mg
• 1 pmol of pBR322 DNA (4361 bp) = 2.88 mg
• 1 pmol of lDNA (48502 bp) = 32.01 mg
Notes: There are 3 ¥109bp in human
genome•35% of human genome is repetitive
DNA sequence; 65% is unique Human
chromosome number (diploid) is 46 (23 pairs)
Equilibrium Frequencies:
Frequencies of dominant allele Aand
recessive allele a among egg and sperm
are pand q(= 1 – p)
COLLEGE GENETICS A-806-01© 1996-2011 Mindsource Technologies Inc.
l e a r n r e f e r e n c e r e v i e w
TM
permacharts
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