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Biology 1403 Test#4
Terms in this set (34)
Def: The expression of both alleles
-RedxWhite=Red & White spotted
When the two alleles inherited from the parents are neither dominant nor recessive, but blend together to give a physical trait that is somewhere between the two
Exception/Extensions to Mendels Rules
-Polygenic inheritance of quantitative traits
>1 Gene Effects a single trait
-strongly affected by environment
-Shows continuous Variation
single gene effects multiple traits
ex: Albanism (pigmentation)-->
What is Pedigree?
A graphic representation of genetic inheritance. A diagram made up of a set of symbols that identify males and females; individuals affected by the trait being studied; and family relationships
Traits controlled by genes located on the sex chromosomes. Patterns of inheritance in males and females differ.
When parents do not show the trait, but have children who do; a generation is skipped
One or both parents show the trait; no generations are skipped
How do you know if a recessive pedigree is sex linked?
More males than females affected; Female carriers pass trait on to male sons
How do you know if a recessive pedigree is autosomal?
Roughly equal numbers of males and females are affected; female carriers pass trait on to BOTH sons and daughters equally
How do you know if a dominant pedigree is sex linked?
Male with trait passes the trait to ALL of his daughters
How do you know if a dominant pedigree is autosomal?
Male with trait DOES NOT pass the trait to all of his daughters
What are the 5 autosomal recessive disorders?
2) Cystic Fibrosis
5) Tay-Sachs Disease
How many recessive alleles do you need to inherit to get recessive disorders?
What are the three sex linked recessive disorders?
1) Color Blindness
3) Duchenne Muscular Dystrophy
Having only a single copy of a gene instead of the customary two copies. All the genes on the single X chromosome in the male are 'hemizygous.'
Heirachy of Genes
Some genes are more important than others
Example: Human Skin Color
A,B,C>(How much melanin is produced)
Tyrosinase gene: converts tyrosine>dopamine>malanine(No tyrosine=No melanine)
Even if you have gene sequence to be very dark, but have the sequence for no tyrosinase>Albino
Anhydrotic Ectodermal Dysplasia
Also-called: Christ-Siemens-Touraine syndrome.
abnormal development of the skin, hair, nails, teeth, or sweat glands.
- X-Linked Recessive
- IKBKG and NFKBIA gene mutations responsible for EDA-ID result in the production of proteins with impaired function, which reduces activation of nuclear factor-kappa-B.
-fathers cannot pass X-linked traits to their sons.
-n females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder.
A mode of inheritance in which a mutation in a gene on the X chromosome causes the phenotype to be expressed in males who are hemizygous for the gene mutation (i.e., they have only one X chromosome) and in females who are homozygous for the gene mutation
(also called lyonization)
-is a process by which one of the two copies of the X chromosome present in female mammals is inactivated.
-X-inactivation prevents them from having twice as many X chromosome gene products as males, who only possess a single copy of the X chromosome
a condensed, inactivated X chromosome present in most female mammals in the nuclei of all cells except the germ cells: used, as in sports competitions, to verify that an individual is genetically female.
A genetic mosaic is a creature whose body is built of a mixture of cells of two or more different genotypes.
-The fusion of two different zygotes, or early embryos, into one.
-also called chimera
A physical barrier that forms around a fertilized egg.
-Prevents fertilization by more than one sperm. (polyspermy)
Sperm entry causes calcium release into the oocyte. In mammals, this has been proposed to be caused by the introduction of phospholipase C isoform zeta (PLCζ) from the sperm cytoplasm, although this remains to be established definitively. Activation of the ovum includes the following events:
-Cortical reaction to block against other sperm cells
-Activation of egg metabolism
-Reactivation of meiosis
cell created by cleavage divisions in early animal embryos.
series of rapid mitotic cell divisions with little cell growth, that produces increasingly smaller cells(blastomeres).
-turns zygote into multicellular blastula
is an embryo at an early stage of embryonic development, consisting of cells (called blastomeres) in a solid ball contained within the zona pellucida.
3 Embryonic (Germ) Tissue Layers
-Ectoderm:(outside), epidermal tissues and nervous system
-Mesoderm: (middle), skeletal tissues , muscle tissues, circulatory, excretory, respiratory, reproductive.
-Endoderm: (inner), interior stomach lining, gastrointestinal tract, the lungs
an interaction between one (inducing) tissue and another (responding) tissue, as a result of which the responding tissue undergoes a change in its direction of differentiation
-Initiates Signal Transduction Pathway(2nd Messenger)
Factors of Inducers
-Identity of Inducer
-Concentration when it arrives @ target tissue
-direction from which it comes and arrives @ target tissue
-Sequence at which inducers arrive @ target tissue
(Apical Ectodermal Ridge)
structure that forms from the ectodermal cells at the distal end of each limb bud and acts as a major signaling center to ensure proper development of a limb. After the limb bud induces AER formation, the AER and limb mesenchyme—including the zone of polarizing activity (ZPA)—continue to communicate with each other to direct further limb development
(Zone of Polarizing Activity)
area of mesenchyme that contains signals which instruct the developing limb bud to form along the anterior/posterior axis. Limb bud is undifferentiated mesenchyme enclosed by an ectoderm covering. Eventually, the limb bud develops into bones, tendons, muscles and joints. Limb bud development relies not only on the zone of polarizing activity, but also many different genes, signals, and a unique region of ectoderm called the apical ectodermal ridge (AER).
-concentration determines type of finger(2nd messenger)
What genetic phenomenon accounts for the fact that neither mitochondria nor chloroplasts can survive outside of their eukaryotic cells? What evidence exists for this phenomenon?
-Neither mitochondria (mt) nor chloroplasts (chl) can survive apart from their surrounding eukaryotic cell because they no longer have all of their genes.
-Some of these genes have been completely lost; others have been moved to the nuclear genome of the surrounding cell by a genetic phenomenon known as "horizontal gene transfer."
-The evidence that supports this is:
+the current genomes of mt and chl are smaller than those of modern alpha-proteobacteria and cyanobacteria, of which these organelles are descendents.
+Moreover, when we search the nuclear genomes of eukaryotes, they contain some genes of alpha-proteobacteria, and when we search the nuclear genomes of plants for cyanobacterial genes, they are there!
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