Ch 1 The Cell Flashcards
Gene pool
Total of all alleles in a population
Evolution
Change in a population’s gene pool
Speciation
Formation of a new species
Inbreeding
Increases number of homozygous individuals in a population without changing the allele frequency
Outbreeding
Mating of nonrelatives, maintains genetic flow between populations, does not contribute to speciation
Bottleneck
Allergic frequencies of a population are shifted, can lead to speciation
Specialization
Process by which members of a species tailor their behaviors to exploit the environment
Hardy-Weinberg equilibrium
- Mutational equilibrium
- Large population
- Random mating
- Immigration or emigration must not change the gene pool
- No selection for the fittest organism
Mutational equilibrium
The rate of forward mutations exactly equals the rate of backward mutations
Genetic drift
One allele can be permanently lost due to death of all of the members that have that allele
Happens in small populations
The success of a gene can be measured…
As its increase in percent representation in the gene pool of the next generation
Differential reproduction
How well an organism can reproduce to contribute its genes to the next generation
May include living beyond reproduction in order to give offspring a better chance to reproduce
Viral particle aka virion
Mature virus outside the host cell
Viruses
- contains DNA OR RNA
- no organelles
- no nuclei
- capsid (protein coat)
- exploits host cells organelles to survive
Virus receptor
Specific glycoprotein on the host cell membrane
Bacteriophage
Virus that infects a bacteria
Two types of viral infections
Lysogenic infection and lytic infection
Lytic viral infection
Virus commanders the cell’s synthetic machinery and forms proteins for itself to make new viruses
Cell either lyses (bursts) or releases virsuses in a reverse endocytotic process
Latent period
Period from viral infection to lysis
Virulent virus
A virus following a lytic cycle
A virus capable of causing disease
Lysogenic viral infection
Viral DNA is incorporated into the host genome
Temperate virus
Virus in a lysogenic cycle
Provirus
A temperate virus that is dormant or latent
Viral envelopes
Pinched off pieces of cell membrane as the virus undergoes exocytosis from the cell
Protects virus from detection by the immune system
Nonenveloped viruses
Lyse and kill a cell upon its release
RNA-dependent RNA polymerase (RdRP)
How all RNA viruses replicate
This enzyme synthesizes a new RNA strand from an existing RNA strand
+RNA
RNA strands that actually code for proteins
-RNA
RNA strand that doesn’t code for proteins
If a virus carries -RNA…
It must undergo one replication by RdRP to form +RNA in order to code for proteins
Retroviruses
Single stranded RNA viruses that transcribe their RNA into double stranded DNA
Reverse transcriptase
Enzyme that retroviruses use to transcribe their RNA into DNA
Subviral particles
Infectious agents related to viruses, eg, viroids and prions
Viroids
Small rings of naked RNA without capsids
Three basic bacterial shapes
Cocci (spherical)
Bacilli (rod shaped)
Spirilla (spiral shaped)
Protoplast
Bacterial membrane and everything it contains
Cell walls of bacteria are made of
peptidoglycan
Peptidoglycan
Series of disaccharide polymer chains with cross linked interbridged amino acids
Gram positive bacteria
- thick peptidoglycan cell walls
- purple
- cell wall located just outside of cell membrane
Periplasmic space
Space between plasma membrane and cell wall
Contains many proteins that help the bacteria acquire nutrition, eg, hydrolytic enzymes
Gram negative bacteria
- thin walls
- pink
- cell wall located between two plasma membranes
- outer membrane is more permeable than the inner one
- some have fimbriae or pili
Flagella
Long hollow rigid helical cylinders made from a globular protein called flagellin
Flagellar propulsion
Powered by a proton gradient rather than ATP, allows bacteria to move towards food source
Chemotaxis
Directed movement of bacteria towards substances that promote survival and growth
Three forms of bacterial genetic recombination
Conjugation
Transformation
Transduction
Conjugation
Involves the transfer of a plasmid
Requires a sex pilus
A bacteria must contain ______ to undergo conjugation
A conjugative plasmid which contains the gene for sex pilus
Two types of plasmids
The F plasmid and the R plasmid
F plasmid
Fertility factor
Codes the gene for the sex pilus
R plasmid
Donates resistance to certain antibiotics
Transformation
Process by which bacteria incorporate DNA from the external environment into their genomes
Transduction
Transfer of genetic material by a virus
