Bio Exam 3 Review

Only available on StudyMode
  • Download(s) : 23
  • Published : March 5, 2013
Open Document
Text Preview
Exam 3 Review Sheet

Genetics terms: phenotype, genotype, allele, dominant, recessive, homozygous, heterozygous, multiple alleles, codominance Phenotype: physical appearance
Genotype: genetic composition
Allele: alternate form of a gene
Dominant: trait that will be expressed
Recessive: trait that will be masked by dominant trait
Homozygous: both alleles are the same
Heterozygous: the alleles are different
Multiple Alleles:
Codominance:
Sex determination – all possibilities
Xyy:
Xxy (klinefelter’s syndrome):
Xo (turners syndrome)
XXX:
One and two trait crosses with punnett squares, sex linked traits\

Questions from “Ghost in your genes video”
Attached on other sheet
Fertilization and polyspermy
Fertilization:
• Sperm squeezes through follicle cells
• Sperm releases acrosomal enzymes so it can penetrate the zona pellucida • Sperm cell membrane fuses with egg cell membrane
• Sperm enters egg, nucleus is released
• Egg nucleus and sperm nucleus fuse forming a zygote
Polyspermy:
More than one sperm fertilizes the egg
Cellular stages of development; Radial and spiral cleavage, formation of blastula Cleavage:
• Mitotic cell divisions yield a ball of cells (blastula); each cell gets a different bit of the egg cytoplasm • Number of cells increases, but the zygote’s original volume remains unchanged • Cleavage takes the embryo from a zygote to a blastula • There are two type of cleavage, radial and spiral, based on the patterns of cell division Radial cleavage:

Division of cells in early embryo to produce cells of equal size Spiral Cleavage:
Division of cells in early embryo to form cells of unequal size Formation of blastula:
Blastula: hollow ball of cells filled with fluid
Pump sodium inside, water flows via osmosis
Not all blastulae look exactly alike

Tissue stages of development: early gastrulation, late gastrulation, germ layers Early gastrulation:
• Migration of cells to form the outer layer (ectoderm) and the inner layer (endoderm) • Blastopore forms
• Blastopore – opening that can become the mouth or the anus Late gastrulation:
• Two layers of cells form the 3 germ layers
• Formation of mesoderm
Three germ layers:
• Three germ layers give rise to the same types of tissues and organs in all vertebrates – evidence of a shared ancestry – ectoderm
• Outermost tissue layer of an animal embryo – endoderm
• Innermost tissue layer of an animal embryo – mesoderm
• Middle tissue layer of a three-layered animal embryo Organ stages of development; nervous system development
Nervous system development
• Mesoderm cells along the dorsal axis form a long rod of cells. • Rod is the notochord which provides support to the nerve cord. • Nervous system develops from ectoderm above notochord. Cells flatten out to form a neural plate, and then invaginate to form neural groove. • Neural groove coalesces to form a neural tube. Anterior end develops into the brain and the rest develops into the spinal cord Cellular differentiation, morphogenesis, pattern formation

Cellular differentiation:
Cells become specialized in structure and function
Morphogenesis:
• Produces the shape and form of the body
• Includes pattern formation
Pattern formation:
• Pattern formation is the process by which certain body parts form in a specific place • Positional information set up by concentration gradients of products of master genes affects expression of homeotic genes, which regulate development of specific body parts Induction and cellular communication

Induction:
1. Notochord forms from mesoderm cells soon after gastrulation is complete 2. Notochord induces the formation of the neural tube (and other structures along dorsal, or back, side of embryo) 3. Formation of neural tube is complete. Cells of notochord are...
tracking img