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Bio Genetics Chapter Test


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during synapsis, the intertwined chromosomes may exchange segments resulting in genetic variations
a sudden change in the structure OR amount of genetic material
what are the effects of mutations
1) most are harmful
2) some have NO effect
3) a few are beneficial
first individual showing the new trait of a mutation
chromosomal mutation
abnormal change in all or part of a chromosome or the # of chromosomes
gene mutation
a change that affects a gene on a chromosome (change in genetic code)
autosomal mutations
mutations in body cell chromosomes-are not passed on to the offspring
causes of mutations (2)
1) random errors in replication
2)environmental factors
ex. radiation (x-ray, ultra violet)
chemicals (chloroform, mustard gas)
part of a chromosome is transfered to a nonhomologous chromosome
-a mutation
-a mutation
-a piece of chromosome is rotated which reverses the order of genes in that segment
-a mutation
-piece of a chromosome breaks off and attaches to its homologous chromosome
-a mutation
-the other half of duplication (when a piece breaks off)
the addition or loss of an ENTIRE chromosome b/c they did not separate normally during meiosis
-a mutation
-cells have multiples of the normal chromosome number (ex. 3n, 4n, 5n)
-non-separation during meiosis-occurs in plants, producing larger than normal fruits
point mutation
-a gene mutation
change at 1 point of a gene (out of 3)
only a single nucleotide switch, add, or subtract
-results in frameshift mutation
3 types of point mutation
a) substitution-switch at one nucleotide
b) insertion- add 1 nucleotide
c) deletion- subtract one nucleotide
frameshift mutation
after point mutation, every codon after this point where a nucleotide is switched, added, or removed, will be different
jumping genes
same genes simply switch loci (spots) onto a different gene-important source of genetic variation
-sex=linked disorder
disease where blood doesnt clot properly-found on the X chromosome
Duchenne Muscular Dystrophy
-muscle tissue breaks down during childhood-most individuals DO NOT survive past their teenage years
sickle-cell disease/sickle-cell anemia
recessive-red blood cells have abnormal sickle shape-block small blood vessels
-inherited-recessive disorder
-enzyme that breaks down phenylalanine is missing-phenylalanine will break down incorrectly, resulting in brain damage and mental retardation
-controlled by diet
tay-sachs disease
-brain damage-enzyme that breaks down lipids is missing-lipids build up in the brain cells and destroy them
cystic fibrosis
the most common inherited disorder among whites-FATAL-no cure
-recessive allele found in chromosome #7
-individual's homozygous recessive produce a thick mucus that clogs and damages the lungers-w/ treatment individuals can live to early adulthood (25 years)
huntington's disease
dominant allele causes progressive breakdown of the brain cells
-results in death
down syndrome
chromosome 21=3 chromosomes
-mental retardation and physical abnormalities (IN EVERY CELL)
turners syndrome
only 1 sex chromsome-X chromsome-female-undeveloped sex characteristics
klinefeters syndrome
-2 x chromsomes and 1 Y chromosome in each cell
-male-underdeveloped sex organs
photograph of mitotic cell-enlarge photo and cut out chromsomes to arrange in pairs
removal of some amniotic fluid-contains fetal cells-examine for problems
ultrasonic sound waves bounce off fetus-investigate for abnormalities
direct observation of the fetus and tissue
a group of organisms that have exactly the same genetic sequence
gene splicing
The technology of preparing recombinant DNA in vitro by cutting up DNA molecules and splicing together fragments from more than one organism.
recombinant DNA
DNA from different species joined together
gene therapy
the correction of genetic defects by transferring normal genes to cells that lack them
living bacteria that are in DNA from dead bacteria-traits from the dead bacteria appeear in the living bacteria
viruses pick up genetic information from an infected bacteria and transfer it to a new bacteria host
choosing a mate w/ desirable traits
mating of closely related individuals to obtain specific traits
individuals not closely related
hybrid vigor (heterosis)
special traits found in hybrid crosses of two close species
where is dna found
where is rna found
composition of DNA
-5 carbon sugar=deoxyribose
-1 phosphate
-4 types of nitrogen bases
4 types of nitrogen bases
adenine, guanine---purines
cytosine, thymine----pyrimidines
basic unit of DNA
how are base pairs held together?
weak hydrogen bonds
history of DNA
watson and rick using a key piece of info-unveiled the structure of DNA-double helix
rosaliud franklin
took x-rays of DNA crystals-these showed a repeating helix pattern
explain replication of DNA
DNA separate into two strands b/c of DNA polymerase (enzyme) --produces free nucleotides that attach to each strand resulting in two strands
how many amino acids are there
how many possible combos of base pairs are there
3 base pair
-thymine replaced by uracil
messenger RNA
reads and carries the genetic code from the dna to the ribosome-mRNA
transfer RNA
transports amino acid molecules to the ribosomes-tRNA
ribosomal RNA
makes up the ribosome
RNA polymerase binds to DNA and separates the DNA strands. RNA polymerase then uses one strand of dna as a template from which nucleotides are assembled into a strand of dna (ex. where there is a cytosine on the DNA, a guanine will be made on an RNA)
before this: in transcription, mRNA joins with an unzipped DNA molecule and interprets the DNA code
TRANSLATION: the mRNA leaves the nucleus through the nucleopore. in the cytoplasm, the mRNA joins w/ ribosomal RNA (ribosome).trna, each coded for a specific codon, joins with its corresponding codon and leaves its amino acid. the amino acid grows with other amino acids to form a polypeptide
that dna segment that will code for a protein
that dna segment that will NOT code for a protein
genes that cause some types of cancer. present in MOST human cells but are dorment
law of independent assortment
genes for different traits are separated and distributed to gametes independently of one another

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