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Growth and Development in Plants and Animals
Cell determination, genetics, aging and dying, Mendel's theories
45
Biology
Undergraduate 1
12/06/2011

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Term
How does physical location of cells in an embryo influence cell determination and differentiation?
Definition
Whether or not there's pressure coming from all sides or not (if it's on the edge or not)
If a cell has pressure coming from all sides, it most likely not undergo cell division. Because if it were to divide, there'd be no room to grow out.
Term
What is one way cancer allows tumors to grow?
Definition
It inhibits the INHIBITION of cells dividing from the inside of a tissue. Thus resulting in tumors inside of a tissue.
Term
How does the neighboring cell's plasmalemma chemical characteristics affect cell differentiation and determination?
Definition
Fats and protein content differs in each cell's plasmalemma, but all the plasmalemma is in contact, so the combinations of these chemicals could make a new type of cell.
Term
morphagen
Definition
chemical released into surroundings, like a hormone
Term
Gradual growth
Definition
Constant rate of growing. Young organism looks like small adult, has internal bones usually
Term
Sporadic growth
Definition
Dramatic rate of growing. Young look dramatically different than adult.
Term
Instar
Definition
Each stage after a period of growth
Term
Metamorphosis
Definition
Last instar before adulthood
Term
2 types of metamorphosis
Definition
1. Incomplete metamorphosis: instar is called a nymph (looks like tiny adult) [ex grasshoppers, roaches, spiders]
2. instar is called a larvae (look like totally different creatures) [ex butterflies, frogs] *Last larval stage is pupa
Term
Pupa
Definition
Last larval stage (in complete metamorphosis.) Contains chunks of adult tissue
Term
Imaginal discs
Definition
Chunks of adult tissue contained in the pupa
Term
6 causes of development (formation of tissues and organs) *Begins in last half of gastrula stage*
Definition
1. cell differentiation 2. amount of cell division 3. shape of cell division (shape of organ etc.) 4. cell migration 5. osmosis 6. apoptosis (programmed cell suicide) *ex. webbing between fingers and toes leaves
Term
Ecdysone
Definition
chemical that makes shell (exoskeleton) harden
*Included in many insectisides, so bugs are crushed against their own shell
Term
Ecdysis (molting)
Definition
process of breaking out of shell
Term
4 Benefits of Complete Metamorphosis
Definition
1. Allows growth with exoskeleton
2. In most cases, the larva eat completely different food, so no competition for food between parent and young
3. Reduced competition for space (parent and young usually occupy different areas)
4. One of the stages is more mobile
Term
9 Hypothesis for why we age and die
Definition
1. Accumulated damage
2. Excessive caloric consumption
3. Decrease in immune system
4. Change in hormonal levels
5. Accumulation of Toxins
6. Accumulation of senescent cells
7. Loss of genes by genetic mutation
8. Loss of genes due to depletion of telomeres
9. Decrease in activity of longevity genes
Term
Accumulated damage hypothesis
Definition
Simplest explanation, includes injuries, viruses, bacteria, alcohol/drugs, over-eating
Term
Excessive caloric consumption
Definition
Studies have shown that starvation actually prolongs life in organisms. (Studies with c. elegans [nematodes])
Term
Decrease in immune system
Definition
Become more susceptible to pathogenic organisms
Term
Change in hormonal levels
Definition
Human growth hormone injections into humans have appeared to reduce effects of aging. This is illegal in US, and most physicians and scientists agree that it's unethical
Term
Accumulation of Toxins
Definition
Each cell constantly makes toxins due to electrons out of ETS joining with o2 in an uncontrolled reaction making a highly reactive oxygen radical that can kill cells. So, humans evolved an enzyme to detoxify it called superoxide dismutase. Changes the oxygen radical to water or oxygen. As you age, you continue to make toxins but less SOD.
Term
Accumulation of senescent cells
Definition
As cells die, they release chemicals that can cause inflammation in the arteries and other cardiac problems
Term
Loss of genes by genetic mutation
Definition
UV light, background radioactivity, exposure to environmental chemicals that cause DNA damage (mutigens) cause mistakes copying during cell division
Term
Loss of genes due to depletion of telomeres
Definition
Every time a cell divides, a bit of the tip of the chromosome gets eaten away, so we created telomeres like caps for the ends that don't contain genes. As you age, these get smaller. Telomerase rebuilds telomeres, but this enzyme shuts down after differentiation.
Term
How many times can a cell divide?
Definition
About 50. Except pluripotent stem cells seem to divide more. *Cancer reactivates its telomerase gene so it can continuously reproduce
Term
Decrease in activity of longevity genes
Definition
studies with nematodes found that these genes become inactive as we age
Term
Telomerase
Definition
Rebuilds telomeres.
Shuts down after cell differentiation.
Plants have active telomerase even after determination.
Term
4 benefits of being a plant?
Definition
1. Have a much greater proportion of undifferentiated cells than animals
2. cell migration is impossible/unnecessary in plants because of cell walls
3. growth of buds in spring produce phloem cells, etc. so it's embryonic growth
4. plants don't seem to die from age
Term
Inheritance
Definition
transmission of info about different traits of an organism from one generation to the next
Term
Gregor Mendel
Definition
Austrian, worked with 28,000 pea plants and crossing them.
Term
Theories of Inheritance (original theories)
Definition
Pangenesis Hypothesis (pieces from each of mom and dad, Homunculus Hypothesis (whole child is in sperm, + egg version as well), Blending Theory
Term
Mendel's 3 Principles
Definition
1. Principle of Segregation
2. Principle of Dominance
3. Principle of Independent Assortment
Term
Principle of Segregation
Definition
For each trait, an individual has 2 "hereditary factors" (Rr, etc) 1 from each parent. These 2 factors are kept segregated during the entire life of the organism, and keep the genes more or less the same (you actually pass your father and mother's genes on)
Term
Principle of Dominance
Definition
For each trait, there are two forms of the hereditary factors: a dominant form, and a recessive form. *Most diseases are recessive
Term
Princple of Independent Assortment
Definition
The way hereditary factors for one trait are inherited (R from the father, r from mother, etc.) has no effect on the way other traits are inherited.
Term
gene
Definition
information that determines the nature of a particular trait. (eye color, disease, proteins etc.) A stretch of DNA
Term
allele
Definition
specific information of the gene. Most genes have 2 (R or r)
Term
locus
Definition
location of a gene on a chromosome
Term
genotype
Definition
allelic composition of an organism. 1 or more genes ex. Rr or RR or rr
Term
phenotype
Definition
what trait is shown (ex. Rr genotype makes round phenotype)
Term
heterozygous
Definition
having different alleles. (ex. Rr)
Term
recombination
Definition
occurs in many chromosome pairs but not all. When chunks of each chromosome at same loci get swapped. Not actually a modification of Princ. 1 because one is still coming from each parent
Term
incomplete dominance
Definition
Sort of blending of the alleles. ex snapdragons R=Red r=white RR=dark red, Rr=pink, rr=white.
Term
Blood types
Definition
Multiple (?) dominance. There are 4 phenotypes for blood, and 3 alleles. IA IA= Type A. IA+i=Type A. IB+IB=Type B IB+i=Type B IA+IB=Type AB i+i=Type O
Term
DNA
Definition
Large molecule stuck to protein is a chromosome, DNA is in chromosome. The "rails of ladder" are sugar phosphate. The "rungs" are Nitrogen based nucleotides A, T, C, G.
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