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BIO 110- EXAM #3
Lecture Exam
99
Biology
Undergraduate 2
03/16/2013

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Term
Pairing of homologous chromosomes and crossing over occurs in which phase of meiosis?
Definition
Prophase 1
Term
Meiosis typically results in the production of:
Definition
4 haploid cells
Term
During which phase of the cell cycle are chromosomes replicated?
Definition
Interphase
Term
Which of the following is the proper sequence for mitosis?
Definition
prophase, metaphase, anaphase, telophase
(PMAT)
Term
Cells have mechanisms to control:
Definition
-cell growth
-DNA replication
-cell division
Term
Various forms of a gene at a given locus are called:
Definition
Alleles
Term
Which of the following designates a normal human male?
Definition
XY
Term
A human X-linked recessive trait may be:
Definition
passed to sons from their mothers
Term
The theory of segregation:
Definition
explains the behavior of a pair of alleles during meiosis
Term
Which of the following indicates homozygous genotypes?
Definition
AA and aa
Term
How do prokaryotic cells reproduce?
Definition
asexually by prokaryotic fission
Term
This copies DNA and divides a nucleus, producing two
identical nuclei
Definition
Mitosis
Term
This is a nuclear division that produces haploid gametes for
sexual reproduction
Definition
Meiosis
Term
A chromosome consists of DNA that is wrapped around ________ and ________
Definition
proteins (histones); condensed
Term
Each histone and the DNA wrapped around it make up a
________, the smallest unit of structural organization in
chromosomes
Definition
nucleosome
Term
A sequence of three stages (interphase, mitosis, and cytoplasmic
division) through which a cell passes between one cell division
and the next
Definition
cell cycle
Term
Consists of three stages, during which a cell
increases in size, doubles the number of cytoplasmic
components, and duplicates its DNA
Definition
Interphase
Term
3 phases of Interphase:
Definition
• G1: Interval of cell growth and activity
• S: Interval of DNA replication (synthesis)
• G2: Interval when the cell prepares for division
Term
Interphase: Most cell activity takes place during __?
Definition
G1
Term
Interphase: Control mechanisms work at certain points in the cell cycle;
some can keep cells in
Definition
G1
Term
Mitosis produces __ ____ _______with the same number and kind
of chromosomes as the parent
Definition
two diploid nuclei
Term
• A dynamic network of microtubules that forms during nuclear
division
• Grows into the cytoplasm from opposite poles of the cell and
attaches to duplicated chromosomes
• Microtubules from opposite poles attach to different sister
chromatids and separate them
Definition
Bipolar spindle
Term
[image]
Definition
[image]
Term
[image]
Definition
[image]
Term
What are the four main stages of mitosis?
Definition
1)prophase

2)metaphase

3)anaphase

4)telophase

PMAT
Term
• Chromosomes condense
• Microtubules form a bipolar spindle
• Nuclear envelope breaks up
• Microtubules attach to the chromosomes
Definition
Prophase
Term
All duplicated chromosomes line up midway between the spindle
poles
Definition
Metaphase
Term
Microtubules separate the sister chromatids of each chromosome
and pull them to opposite spindle poles
Definition
Anaphase
Term
• Two clusters of chromosomes reach the spindle poles
• A new nuclear envelope forms around each cluster
• Two new nuclei are formed, each with the same chromosome
number as the parent cell
Definition
Telophase
Term
[image]
Definition
[image]
Term
[image]
Definition
[image]
Term
[image]
Definition
[image]
Term
[image]
Definition
[image]
Term
[image]
Definition
[image]
Term
[image]
Definition
[image]
Term
In most kinds of eukaryotes, the cell cytoplasm divides
between late ________ and the end of ________, but the
mechanism of division differs
Definition
anaphase; telophase
Term
The process of cytoplasmic division is called _____________.
Definition
Cytokinesis
Term
Animal cells:
• A ________ _____ partitions the cytoplasm
• A band of _____ _______ ________ the cell midsection, contracts, and
pinches the cytoplasm in two
Definition
contractile ring; actin filaments rings
Term
Plant cells:
• A _____ _______ forms midway between the spindle poles; it partitions the
cytoplasm when it reaches and connects to the parent cell wall
Definition
cell plate
Term
________ can activate other molecules to stop the cell cycle or
cause cells to die
Definition
Kinases
Term
_______ _______ can activate kinases to start mitosis
Definition
Growth factors
Term
When all checkpoint mechanisms fail, a cell loses control over
its cell cycle and may form a ___________ in
surrounding tissue
Definition
tumor(abnormal mass)
Term
• Abnormal masses of cells that lack control over how they grow
and divide
• Benign neoplasms (such as ordinary skin moles) stay in one place
and are not cancerous
• Malignant neoplasms are cancerous
Definition
Neoplasms
Term
• Cells grow and divide abnormally; capillary blood supply to the
cells may increase abnormally
• Cells may have altered plasma membrane and cytoplasm;
metabolism may shift toward fermentation
• Cells have altered recognition proteins and weakened adhesion;
may break away and invade distant tissues (metastasis)
Definition
Cancers (malignant neoplasms)
Term
_______ ________ produces genetically identical copies of
a parent (clones)
Definition
Asexual reproduction
Term
_______ ________ introduces variation in the combinations
of traits among offspring
Definition
Sexual reproduction
Term
_______ are regions in an organism’s DNA that encode
information about heritable traits
Definition
Genes
Term
_______ are different forms of the same gene
Definition
Alleles
Term
A nuclear division mechanism that precedes cytoplasmic division
of immature reproductive cells in sexually-reproducing eukaryotic
species
Definition
Meiosis
Term
A ______ ______ has two nonidentical copies of every chromosome
(except XY sex chromosomes)
Definition
diploid cell
Term
Meiosis in germ cells halves the diploid number of chromosomes
(2n) to the haploid number (n), producing haploid gametes
• Eggs and sperm have 23 unpaired chromosomes
Definition
Term
The diploid number (23 pairs) is restored at fertilization, when
two haploid gametes fuse and form a diploid _______, the first
cell of a new individual
Definition
zygote
Term
In meiosis, DNA is replicated once and divided twice (meiosis I
and meiosis II), forming _____ haploid nuclei
Definition
four
Term
[image]
Definition
[image]
Term
[image]
Definition
[image]
Term
[image]
Definition
[image]
Term
• The process by which a chromosome and its homologous partner
exchange heritable information in corresponding segments
• Occurs during condensation in prophase I
Definition
Crossing over
Term
[image]
Definition
[image]
Term
Diploid bodies with specialized structures that form spores
(haploid cells) that give rise to gametophytes through mitosis
Definition
Sporophytes
Term
A multicelled haploid body inside which one or more gametes
form
Definition
Gametophytes
Term
_______ cells (chromosome number 2n) have pairs of genes on
homologous chromosomes
Definition
Diploid
Term
A ________ is a permanent change in a gene
Definition
mutation
Term
A ________ has nonidentical alleles for a trait
Definition
hybrid
Term
An allele is ________ if its effect masks the effect of a
recessive allele paired with it
Definition
dominant
Term
Garden pea plants inherit ____ “units” of information for a
trait, one from each parent
Definition
2
Term
• A method of determining if an individual is heterozygous or
homozygous dominant
• An individual with unknown genotype is crossed with one that is
homozygous recessive (AA x aa) or (Aa x aa)
Definition
Testcross
Term
• Testcrosses that check for a dominance relationship between two
alleles at a single locus
• May be crosses between true breeding (homozygous) individuals
(AA x aa), or between identical heterozygotes (Aa x Aa)
Definition
Monohybrid experiments
Term
• Diploid cells have pairs of genes on pairs of homologous
chromosomes
• The two genes of each pair separate during meiosis, and end up
in different gametes
Definition
Mendel’s law ofsegregation
Term
Many genes are sorted into gametes independently of other
genes
Definition
Mendel’s law of independent assortment
Term
• Tests for dominance relationships between alleles at two loci
• Individuals that breed true for two different traits are crossed
(AABB x aabb)
• F2 phenotype ratio is 9:3:3:1 (four phenotypes)
• Individually, each dominant trait has an F2
ratio of 3:1 –
inheritance of one trait does not affect inheritance of the other
Definition
Dihybrid experiments
Term
• Two nonidentical alleles of a gene are both fully expressed in
heterozygotes, so neither is dominant or recessive
• May occur in multiple allele systems
Definition
Codominance
Term
• Genes with three or more alleles in a population
• Example: ABO blood types
Definition
Multiple allele systems
Term
• One allele is not fully dominant over its partner
• The heterozygote’s phenotype is somewhere between the two
homozygotes, resulting in a 1:2:1 phenotype ratio in F2 offspring
Ex) Snapdragon color
• RRis red
• Rris pink
• rris white
Definition
Incomplete dominance
Term
• Two or more gene products influence a trait
• Typically, one gene product suppresses the effect of another
• Example: Coat color in dogs
• Alleles B and b designate colors (black or brown)
• Two recessive alleles ee suppress color
Definition
Epistasis
Term
• One gene product influences
two or more traits
• Example: Some tall, thin
athletes have Marfan
syndrome, a potentially fatal
genetic disorder
Definition
Pleiotropy
Term
The ________ apart two genes are on a chromosome, the more
often crossing over occurs between them
Definition
farther
Term
• All genes on one chromosome
• Linked genes are very close together; crossing over rarely occurs
between them
Definition
Linkage group
Term
• Traits with a range of small differences
• The more factors that influence a trait, the more continuous the
distribution of phenotype
Definition
Continuous variation
Term
When continuous phenotypes are divided into measurable
categories and plotted as a bar chart, they form a bell-shaped
curve
Definition
Bell curve
Term
The _____ gene on the Y chromosome is the master gene for
male sex determination
• Triggers formation of testes, which produce the male sex
hormone (testosterone)
• Without testosterone, ovaries develop and produce female sex
hormones (estrogens)
Definition
SRY
Term
• A micrograph of all metaphase chromosomes in a cell, arranged
in pairs by size, shape, and length
• Detects abnormal chromosome numbers and some structural
abnormalities
Definition
Karyotype
Term
A ______ ______ ______ is expressed in homozygotes and heterozygotes
• Tends to appear in every generation
• With one homozygous recessive and one heterozygous parent,
children have a 50% chance of inheriting and displaying the trait
• Examples: achondroplasia, Huntington’s disease
Definition
dominant autosomal allele
Term
_______ _______ _______ are expressed only in homozygotes; heterozygotes are carriers and do not have the trait
• A child of two carriers has a 25% chance of expressing the trait
• Example: galactosemia
Definition
Autosomal recessive alleles
Term
Most __________ disorders do not follow simple patterns of Mendelian inheritance
• Depression, schizophrenia, bipolar disorders
Definition
neurobiological
Term
X chromosome alleles give rise to phenotypes that reflect
________ patterns of inheritance
Definition
Mendelian
Term
More ______ than _______ have X-linked recessive genetic disorders
• Males have only one X chromosome and can express a single
recessive allele
• A female heterozygote has two X chromosomes and may not
show symptoms
Definition
males; females
Term
DNA sequences are repeated two or more times; may be caused by unequal crossovers in prophase I
Definition
duplication
Term
Loss of some portion of a chromosome; usually causes serious
or lethal disorders
• Example: Cri-du-chat
Definition
deletion
Term
Part of the sequence of DNA becomes oriented in the reverse
direction, with no molecular loss
Definition
inversion
Term
Typically, two broken chromosomes exchange parts (reciprocal
translocation)
Definition
translocation
Term
Too many or too few copies of one chromosome
Definition
Aneuploidy
Term
Three or more copies of each chromosome
Definition
Polyploidy
Term
• Changes in chromosome number can be caused by
__________, when a pair of chromosomes fails to separate
properly during mitosis or meiosis
Ex)
• Monosomy (n-1 gamete)
• Trisomy (n+1 gamete)
Definition
nondisjunction
Term
• A standardized chart of genetic connections
• Used to determine the probability that future offspring will be
affected by a genetic abnormality or disorder
Definition
Pedigree
Term
A rare or uncommon version of a trait; not inherently life
threatening
Definition
Genetic abnormality
Term
An inherited condition that causes mild to severe medical
problems, characterized by a specific set of symptoms (a
syndrome)
Definition
Genetic disorder
Term
• Starts with parental genotypes, pedigrees, and genetic testing for
known disorders
• Information is used to predict the probability of having a child
with a genetic disorder
Definition
Genetic counseling
Term
Three types of prenatal diagnosis
Definition
• Amniocentesis
• Chorionic villus sampling (CVS)
• Fetoscopy
Term
(widespread, routine testing for alleles associated with genetic disorders)
• Provides information on reproductive risks
• Identifies family members with a genetic disorder
• Used to screen newborns for certain disorders
• Used to estimate the prevalence of harmful alleles in a
population
Definition
Genetic screening
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