Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
56 Cards in this Set
- Front
- Back
|
What is a gene?
|
unit of information about specific traits
|
|
|
On a chromosome, each gene has a ______.
|
locus
|
|
|
What are alleles?
|
various molecular forms of a gene for the same trait?
|
|
|
Non-identical alleles produce ________ offspring.
|
hybrid
|
|
|
What is the genotype?
|
sum of the genes
e.g. Aa |
|
|
What is the phenotype?
|
how the genes are expressed (what you observe)
e.g. tall |
|
|
What is this?
offspring inherit identical alleles, generation after generation |
true-breeding lineage
|
|
|
What is Mendel's theory of segregation?
|
1. states that 2n organisms inherit two genes per trait located on pairs of homologous chromosomes
2. during meiosis the 2 genes segregate from each other such that each gamete will receive only one gene per trait from each parent |
|
|
What is this?
the chance that each outcome of a given event will occur is proportional to the number of ways in which the event can be reached |
probability
|
|
|
What is Mendel's theory of independent assortment?
|
during meiosis, each gene of a pair tends to assort into gametes independently of other gene pairs located on nonhomologous chromosomes
|
|
|
Explain incomplete dominance.
|
a dominant allele cannot completely mask the expression of another
e.g. purebreeding red (RR) parent crossed with purebreeding white (rr) parent equals pink (Rr) F1 generation F2 generation: Rr crossed Rr equals 1:2:1 ratio = 1 white, 2 pink, 1 red |
|
|
Explain codominance.
|
both alleles are expressed in heterozygotes (e.g. AB blood type)
|
|
|
What is this?
Sometimes the expression of alleles at one location can have effects on two or more traits |
pleiotropy
e.g. sickle cell anemia |
|
|
What is this?
One gene pair can influence other gene pairs, with their combined activities producing some effect on phenotype |
epistasis
e.g. hair color in labrador retrievers: one gene pair codes for quantity of melanin produced while another codes for melanin deposition or comb shape in roosters |
|
|
Homologous chromosomes are alike in _______, _________, and _______.
|
length, shape, gene sequence
|
|
|
Independent assortment occurs during which phase of meiosis?
|
metaphase I
|
|
|
Human females are ____gametic.
|
homo
(XX) |
|
|
Human males are _____gametic.
|
hetero
(XY) |
|
|
Who confirmed that each gene has a specific location on a chromosome (linkage)?
|
Thomas Hunt Morgan
(experimented with Drosophila -white-eyed flies) |
|
|
Sex chromosomes are nonidentical but still _________.
|
homologous
|
|
|
Eye-color in flies is ____.
|
sex-linked
|
|
|
Explain autosomal recessive inheritance.
|
Heterozygotes are symptom-free, but carriers.
Homozygotes are affected. |
|
|
Huntington's Disease is an example of what kind of inheritance?
|
autosomal dominant
|
|
|
Name two characteristics of X-Linked Recessive Inheritance.
|
1. mutated gene occurs only on the X chromosome.
2. Heterozygous females are phenotypically normal; males are more often affected because the single recessive allele (on the X chromosome) is not masked by a dominant gene. 3. son cannot inherit disorder from his father. e.g. color blindness |
|
|
Name this structural change.
gene sequence that is repeated several to hundreds of times |
duplication
|
|
|
Name this structural change.
a linear stretch of DNA is reversed within the chromosome ABCDEFG ABDFEDG |
inversion
|
|
|
Name this structural change.
a piece of one chromosome becomes attached to another nonhomologous chromosome -most are recripocal |
translocation
|
|
|
Name this structural change.
loss of some segment of a chromosome -most are lethal or cause serious disorder |
deletion
|
|
|
Changes in chromosome number:
individuals have one extra or loss chromosome (2n + 1 or 2n - 1) |
aneuploidy
|
|
|
Changes in chromosome number:
individuals have 3 or more of each type of chromosome (3n, 4n) |
polyploidy
|
|
|
Changes in chromosome number:
occurs at anaphase I or anaphase II -uneven separation of chromosomes or chromatids |
nondisjunction
(e.g. Klinefelter Syndrome) |
|
|
Explain Fred Griffith's experiments.
|
working with S (pathogenic) and R (harmless) strains on mice
*live R cells plus heat-killed S cells were injected into mice; mice died; live S cells were found in the blood =some substance from the S cells had transformed the R cells Oswald Avery showed that the substance was DNA |
|
|
Viruses called _______ use bacterial cells for reproduction.
These viruses were used in experiments by ______________ to prove which of these was the hereditary material (It was the nucleic acid). |
bacteriophages
Hershey and Chase |
|
|
T and C are single-ring _________.
|
pyrimidines
|
|
|
A and G are double-ring _________.
|
purines
|
|
|
DNA Replication is _________.
|
semi-conservative
|
|
|
DNA is two nucleotide strands held together by ________ bonds.
|
hydrogen (which are easily broken)
|
|
|
DNA Replication and Repair
What unwinds the 2 strands of DNA? |
enzymes
|
|
|
DNA Replication and Repair
What attaches complementary nucleotides to the growing strand? |
DNA polymerase (enzyme)
|
|
|
DNA Replication and Repair
What seals new short stretches of nucleotides into one continuous strand? |
DNA ligases (enzyme)
|
|
|
DNA polymerase always goes in _' to _' direction.
|
5' to 3' direction
|
|
|
DNA Replication and Repair
What is the function of SSB proteins? |
keep DNA polymerases apart
|
|
|
Centrifugation separates substances based upon what characteristic?
A.Cell structure B.Density C.Molarity D.Intergral proteins E.Mass |
B.Density
|
|
|
For Mendels' explanation of inheritance to be correct,
a.the genes for the traits he studied had to be located on the same chromosome b.which gametes combine at fertilization had to be due to chance c.genes could not be transmitted independently of each other d.only diploid organisms would demonstrate inheritance patterns |
b.which gametes combine at fertilization had to be due to chance
|
|
|
If Mendel had not examined the ____ generation, he would not have discovered his theory of segregation.
|
F2
|
|
|
Mendel would not likely have seen 4 different phenotypes in the F2 generation of his dihybrid crosses if
a.the genes had been tightly genetically linked b.the P1 generation had been homozygous c.purple had been dominant to white d.more than 2 traits were traced |
A.the genes had been tightly genetically linked
|
|
|
What fraction of the time will the cross of AaBbCc with AaBbCc produce an offspring that expresses all three dominant genes?
|
27/64
|
|
|
The usual F2 phenotypic ratio of a dihybrid cross is:
|
9:3:3:1
|
|
|
A bell-shaped curve of phenotypic variation is indicative of:
a.incomplete dominance b.continuous variation c.multiple alleles d.epistasis e.environmental variables on phenotypes |
b.continuous variation
|
|
|
Chromosomes other than those involved in sex determination are known as:
|
autosomes
|
|
|
True/False.
The closer together genes are found on a chromosome the greater is the chance that crossing over will occur between them. |
false
|
|
|
Amniocentesis involves sampling
a.the fetus directly b.the fetal cells floating in the amniotic fluid c.sperm d.blood cells e.placental cells |
b. the fetal cells floating in the amniotic fluid
|
|
|
DNA strands serve as which of the following during DNA synthesis?
a. replicate b. substitute c. template d. sources of nucleotides e. all of these |
c. template
|
|
|
Bacteriophages are
a.large bacteria b.pathogens c.viruses d.cellular components e.protistans |
c.viruses
|
|
|
Which of the following does NOT belong with the other four?
a.inversion b.polyploidy c.deletion d.duplication e.translocation |
b.polyploidy
|
|
|
The failure of chromosome to separate during mitosis or meiosis is called:
|
nondisjunction
|
