Random Bio 2

• Define genotype


  The genetic constitution of an organism (the alleles it has for a gene)
• Define phenotype


  The expression of the genes and its interactions with the environment.
• Define homozygous 


  A pair of homologous chromosomes carrying the same alleles for a single gene.
• Define heterozygous


  A pair of homologous chromosomes carrying two different alleles for a single gene.
• Define recessive allele


  An allele only expressed if no dominant alleles are present
• Define dominant allele


  An allele that will always be expressed in the phenotype
• Codominant


  Both alleles are equally dominant and expressed in the phenotype.
• Multiple alleles


  More than two alleles for a single gene
• A sex-linkage


  A gene whose locus is on the X chromosome
• Autosomal linkage


  Genes that are located on the same chromosome (not the sex-chromosome)
• Epistasis


  When one gene modifies or masks the expression of a different gene at a different locus.
• Gene pool


  All the alleles of all the genes within a population at one time
• Population


  All the individuals of one species in one area at one time
• Allele frequency


  The proportion of an allele within the gene pool
• What does the Hardy-Weinberg equation assume?

  No migration to introduce/remove alleles

  No mutations to create new alleles

  No selection of favourable alleles

  Mating is random

  Population is large
• What is speciation?


  The process that leads to the creation of a new species when the original species population is separated and become reproductively isolated.
• Habitat


  Part of an ecosystem in which particular organisms live
• Community


  All the populations of different species in the same area at the same time
• Ecosystem


  A community and the non living components of an environment (biotic and abiotic factors). Ecosystems can range in size.
• Niche


  An organisms role within an ecosystem, including their position in the food web and habitat. Each species occupies their own niche governed by adaptation to both abiotic and biotic conditions.
• Carrying capacity


  The maximum population size an ecosystem can support.
• Abiotic factors


  Non living conditions of an ecosystem
• Biotic factors


  Impact of the interactions between organisms.
• What do muscles act in?

  Antagonistic pairs
• Features of the myofibrils

  Shared nuclei

  Shared cytoplasm (sarcoplasm)

  Many mitochondria
• Which protein is associated with actin?

  Tropomyosin
• Where are calcium ions released from?

  Sarcoplasmic reticulum
• What do calcium ions do?

  Bind to troponin, on tropomyosin, to expose binding sites for myosin heads.
• What is ADP needed for?

  It attaches to myosin heads so that they can bind to myosin to form actinomyocin cross bridges
• Why is there tension in cross bridges?What does this cause?

  Myosin heads bind at an angle causing actin to slide over myosin. ADP is then released
• What happens when ATP binds to myosin heads?

  They detach from the binding site
• What role does ATPase play?

  Hydrolyses ATP into ADP and Pi so the process can be repeated
• What happens when there's an insufficient ATP for muscles?

  Phosphocreatine store loses phosphate group to regenerate ATP form ADP
• Slow twitch fibres


  Rich in myoglobin and mitochondria

  Has a more dense blood supply

  Provides energy over a longer period of time
• Fast twitch muscle fibres

  Has a phosphocreatine store

  Provides short bursts of energy
• What protein(s) are in the A band

  Actin and myosin
• What protein(s) are in the I band

  Actin
• What protein(s) are in the H zone?

  Myosin
• Where does the LDR occur?

  Thylakoid
• Where does the Calvin cycle occur?

  Stroma of chloroplast