BIMM 120 Midterm 1

What is the first law of biology?

all living organisms obey the law of thermodynamics (no such thing as temporary creation + organism in equilibrium = dead)

What is the second law of biology?

all living organisms have membrane-encased cells (cell is the only structure that can divide and is all programmed by genetic instructions)

What is the third law of biology?

life is an evolutionary process (genetic code is universal + derived from common ancestor)

What is the timeline of life on Earth?

bacteria → archaea → eukaryotes

eukaryotes originated from Asgard archaea (important towards precursors of early eukaryotic cells; endosymbiosis of bacteria & archaea)

What is the difference between cooperation and competition in reference to symbionants in Earth life?

Cooperation involved mutual benefit for both organisms while w/ competition, one organism benefited more from the relationship

Did cooperation or competition play more of a role in symbiotic relationships in Earth life?

cooperation played more of a role

How did evolution lead fo creating simple organisms to more complex ones?

symbiotic relationships caused cooperative interactions and gene sharing to create complex forms of organisms

What is the difference between parasitic bacteria Bex and Bba?

Bex = B. exovirus which attaches to outer surface of outer membrane of host to use nutrients for growth

Bba = B. bacteriovorus which penetrates outer membrane to grow in the periplasm; phase: attacks, penetrates, grows in periplasm & cell division

What is the significance of Asgard archaea in evolution pertaining to eukaryotes?

the close evolutionary relationship between organisms show that Asgard archaea have lots of similarities between archaea and eukaryotes + genes considered for eukaryotic signature proteins (endosymbiosis evidence)

What are the characteristics of CPR?

• endosymbiotic/symbiont lifestyle

• needs to live on the surface of another organism for survival because of its small genome and size

• unusual ribosome compositions (missing universal ribosomal proteins)

• limited metabolic capacities because they are shared

What is the Endosymbionant theory?

two or more organisms combine metabolic capacities into one cell that has more evolutionary potential than either of them combined

How does increasing the amount of transmembrane segments give rise to more complex carriers from simple channels?

these segments allow for duplication of simple protein channels to regulate transports → need for protein carriers for regulation

What are the two theories of genetic conservation that are postulated?

• frozen accident: codon reassignment gave rise to harmful effects on translation, decreasing robustness of standard code

• horizontal gene transfer: exchange of genetic material to increase chances between bacteria due to stressful conditions in moderation

Overview of COVID-19

• ACE-2 receptor corresponds to host & spike protein from pathogen binds to this

• originated in Wuhan, China in wet markets w/ close, poor sanitary conditions caused it to transfer to different organisms and humans (zoonotic)

Overview of Influenza

• H1N1 = swine/Spanish flu (spread through pigs that can mix genetic strains) that is most prevalent but immunity/vaccines available to prevent

• H5N1 = avian flu (spread thru birds) that has a high fatality rate and the most recent strain doesn’t have any immunity yet

What is the intermediate host of MERS?

the camel

Overview of Marburg and Ebola

• both are RNA filoviruses

• fatally infectious to humans and primates because it is paired up with high mutable abilities to expand the host’s range to cause hemorrhagic fever

Overview of Prion Diseases

• starts off with misfolding/self-propagating/post-translational modifications of proteins in Peyer Patches to trigger chain reaction with other proteins

• causes BSE (Bovine spongiform encephalopathy), Mad Cow’s Disease, or Creutzeldt-Jakob disease

Overview of Polio

• causes paralysis when it enter the bloodstream to result in muscle atrophy (death of motor neurons)

• Salk (heat killed vaccine) and Saban (attenuated vaccine; virus grown to lose pathogenicity but contains antigens) vaccines created to allow protection from pathogen

Why do viruses want to increase pathogenicity and not virulence?

point is to increase pathogenicity, so by decreasing the lethality it is, viruses can use their host to replicate as many as possible

Have any diseases from plants affected humans?

No

Why are so many diseases zoonotic?

• wet markets: live animals in stressful, unsanitary conditions allows viruses to evolve and infect others nearby

• bush meat: increased contact with infected meat, hunting also destroys wildfire to increase viral infection

• agriculture: close, unsanitary conditions leads to increased risk of viruses jumping to different organisms

Why are bats good reservoirs for diseases?

they coexist with pathogens rather than fight them (constitutive high interferon expression with low inflammation creates commensal infections rather than lethality)

What types of mechanisms do bats have to live alongside infections rather than die from them?

• high temperature to combat viral complications

• high antioxidants to combat oxidative stress

• good DNA repair mechanisms

What is the difference btween antigenic shift and drift?

• antigenic shift: combination of genetic components from different viruses in the same host cell to make something new (recombination)

• antigenic drift: gradual change in mutations to lead to adaptations (large point mutations → variation)

Why is there a flu vaccine needed every year?

Strains of influenza can mutate rapidly so to combat this, a new vaccine is created every year to help with immunity

What mechanism does influenza use that causes the need for new vaccines?

antigenic shift

What is the difference between purines and pyrimidines?

• purines: 2 ringed structures, G + A

• pyrimidines: 1 ringed structure, U + C

Why is the P2 codon position the most important position?

it species the type of amino acid (T = hydrophobic, A = hydrophilic, C & G = semi polar)

What scenario has it where P3 isn’t the wobble position?

in initiation where the P1 position is

What bond strength is stronger in mRNA and tRNA?

• mRNA = pyrimidine

• tRNA = purine

What is the difference in H-bond strength of CG and AT?

• A-T = 2 H-bonds

• C-G = 3 H-bonds

What types of codons are used for gene expression?

• highly expressed genes = common/abundant codons at high frequency

• lowly expressed genes = rare codons at high frequency