Lecture 1 - The Cell Flashcards
Classification system
Domain Kingdom Phylum Class Order Family Genus Species
All mammals belong to the class _________ and the phylum __________
Mammalia; Chordata birds are in Chordata too but in class Aves
Kingdoms in Eukarya
Protista, Fungi, Plantae, Animalia
Species
if can produce fertile offspring with one another
Barriers to producing fertile offsprings
- geographic isolation
- temporal isolation (different seasons)
- genetic incompatibility (gametes do not form viable offspring); ex: mule = female horse and male donkey)
Cell theory
- smallest basic unit life
- shared by all living things
Polymorphism
- gene that has multiple alleles corresponding to distinct forms of a phenotype
- existence in the population makes evolution and speciation possible
Gene pool
total of all alleles in a population
-> evolution = change in a population’s gene pool
Speciation
- evolution can lead to this
- formation of new species
Inbreeding
- mating of relatives
- increases # of homozygous indivs in a population without changing allele frequency
- can lead to speciation (ex: if population divided into groups and mutation occurs in one group but not the other)
Bottleneck
- can lead to speciation (randomly)
- when a disaster occurs in which few survivors (allele frequency not representative of original population)
Specialization
process by which the members of a species tailor their behaviours to exploit their environment
Genetic or behavioural changes that are advantageous in the given environment can lead to speciation
Adaptation
Hardy-Weinberg equilibrium
- theoretical population in which no evolution would occur
1. mutational equilibrium (rate of fwd mutations = back mutations)
2. large population
3. random mating (lack of sexual selection)
4. immigration or emigration must not change the gene pool (no introduction or decline of alleles)
5. no selection for the fittest organism - *when one is broken, evolution occurs
T or F. Large populations are subject to genetic drift
F, small!
Genetic drift
where one allele may be permanently lost due to the death of all members having that allele
Driving principle of natural selection
genes that are advantageous in a given environment are preferentially passed down from generation to generation
Differential reproduction
giving offspring a better chance to reproduce
Viral particle or Virion
mature virus outside host cell
Viruses are comparable to …
nuclei of a cell; exploits organelles around it to synthesize protein and metabolize nutrients
when a virus is inside a cell = extra nucleus
Structure of a virus
- capsid
- tail, base plate, tail fibers
- nucleic acid
- lipid-rich protein envelope for some
Virus following a lytic cycle
virulent; disease-causing
Viral envelopes
- made from host cell membrane; through exocytosis
- protects enveloped virus from immune system
- receptors on envelope allow it to bind to a new host cell and start all over again
- original cell doesn’t die right away but due to the degradation of its membrane will eventually die
- unlike nonenveloped viruses where their release does cause the death of host cell (lyse cell)
Small rings of naked RNA without capsids, which only infect plants
Viroids
prions in animals (naked proteins)
