Bio Mocks 2 Flashcards
(25 cards)
Why are viruses considered living/non-living
Do viruses have a common ancestor?
Non-living: can’t reproduce without a host, can’t perform metabolic reactions on their own, aren’t made of cells, don’t develop/grow over time like living organisms
Living: can adapt/evolve due to mutations like living organisms
It is likely that viruses did not have a common ancestor because they are so different from each other. Scientists think that they evolved spontaneously unlike organisms that share a common ancestor.
what are some common features of viruses
Even though viruses are so different from each other, they have similarities.
- Usually small from 20 to 300 nm
- no growth (size is fixed)
- Nucleic acids: dna or rna
- protein capsids : made of subunits and protect the virus’s genetic material
- no cytoplasm nor ribosomes because their hosts do everything for them
Due to the difference of viruses, they can either have dna or rna and the way they use it can differ. Also, they have either have an envelope or none (protects the virus).
What is the lytic cycle of viruses
starts off attaching itself to the host cell via protein compatibility.
Injects its genetic material into the host cell leaving the protein capsid outside of the host cell.
That DNA gets replicated
Transcription of DNA to mRNA occurs
Translation of mRNA to proteins (the full on virus) occurs
Lysis (the viruses burst out of the host cell and kills the host cell. They find other host cells to start the lytic cycle.
This occurs in plants and animals
Viruses if too virulent can run out of host cells.
If not virulent enough, immune system can kill it
must be the perfect medium of virulence
What is the two different types of evolution? Which one applies to viruses?
How do scientists theorize that viruses were formed?
Divergent evolution: a common ancestor evolved and diverged into different species
–> we don’t think this applies to viruses because of their differences and that they have to have come from different ancestors
Convergent evolution: different species from different ancestors evolved to express similar traits due to their environments.
–> we think this applies to viruses as they all need host cells hence they created something that mimics the universal genetic code of organisms. Hence, they all developed that similar trait. Some think that the universal code implies a common ancestor.
Progressive theory: viruses were made of modified cell components ( different parts of cells came together to create a virus)
Regressive theory: a virus came come a cell that lost some of its cell components.
Do viruses evolve quickly? What would allow them to do so? Does DNA or RNA allow for quicker mutations? What does natural selection favor in viruses?
Viruses evolve super quickly meaning vaccines and immune system aren’t as effective due to their many variants.
What allows them to evolve quickly is their short generational time meaning they live for a short period but they can have many generations within a certain timeframe. This means they can copy their genetic code and mutate a lot.
RNA mutates super quickly because they don’t have complementary base pairs nor do they go through proofreading.
Natural selection favors viruses that have the gene that allows them to evade the immune system.
Explain influenza and HIV
Influenza virus
–> utilizes RNA (rna makes mutations occur faster)
–> has eight molecules of RNA (mutations increase)
–> The mutations in RNA can change the form of its antigens allowing the antigens to progressively attach to new and different cells (different strains). This allows it to be transmitted between species and you can catch the virus multiple times due to the different strains.
–> vaccines need to be updated frequentley for each strain
HIV virus
–> Uses RNA but reverse transcribes into DNA, evading the proofreading process (lead to more mutations)
–> the enzymes of the host can also lead to more mutations
–> you can get infected multiple times because of the new strains and they can also combine to create new strains. This means the immune system can be ineffective and the HIV virus can become drug resistant as they mutate and adapt.
Explain the need for movement for living things
Need to reproduce, find food, etc.
Sessile: stays in one place
Locomotion: moves from place to place
motile: organism that can move from place to place
There can be a combination of both.
Passive: moved by wind or ocean
Active: Muscle movements
Explain the structure of skeletal muscles
(straited muscles) multinucleate, specialized endoplasmic reticulum
Made of many myofibrils and myofibrils are made of repeating unites of sarcomeres that are attached to each other from end to end.
A sarcomere is made of protein filaments
- actin (thin, 7nm, and has a binding site)
- myosin (think, 15 nm, and has a bulbous head)
- Z lines which attaches to actin
Explain how skeletal muscles contract. What is the importance of ATP?
draw myofibril when it is contracted vs when relaxed the sarcomere will be shortened when contracted (z lines come closer)
1) an action potential will tell myofibril to contract. This causes calcium ions to be released from sarcoplasmic recticulums and surround actin molecules. Then it will activate troponin and that will tell the tropomyosin within binding site of actin to be released.
2) ATP becomes ADP + Pi on the bulbous head of the myosin. This charges the bulbous head. This then causes it to bind with the binding site of actin (cross bridge formation). The bulbous head will flex 45 degrees towards the center so that actin is shortened so that myofibril contracts. (the flexing is called a power stroke).
3) ATP will attach to myosin bulbous head and get hydrolyzed to ADP + Pi by an enzyme called ATPase from the bulbous head. This detaches the bulbous head from the binding site and it straightens. This releases the myofibril from the contracted state.
This process will repeat itself so that the actin will move closer and closer towards the center.
We know that ATP is used to relax the muscle, rather than contract it, because after you die, you go into rigor mortis (contraction of muscles). After you die, you don’t produce ATP hence you can’t break cross bridges and relax myofibrils.
Explain antagonistic muscles and titan proteins
Antagonistic muscles are opposite muscles to each other. We need an antagonistic muscle to relax the contracted muscle. (Biceps and triceps)
- When biceps are contracted/flexed, triceps relax and stretch and viceversa.
- The antagonistic muscle (tricep) flexes/contracts causing the sarcomeres/titan proteins to stretch and lengthen, relaxing the biceps
Titan proteins: largest protein, 27000 amino acids
- stabilize myosin within sarcomeres to the Z lines
- help recoil muscles
- build elastic energy when stretched to eventually recoil
- prevents the muscle from over stretching when in a relaxed state.
How is an actional potential reached within a neuron cell?
membrane potential is usually at resting potential of -70 mV.
The threshold potential is -50 mV.
If the potential difference in mV gets to -50 or more, the action potential is reached as the neuron gets depolarized (voltage-gated sodium ion channels open and sodium causes the cell membrane to become more positive). Then, it will repolarize and go back to resting potential.
*draw oscilloscope trace diagram)
Explain the structure of a neuron and how the action potential affects the neuron for neural signaling.
Explain what oscilloscope does
- draw neuron and label*
- soma, nucleus, dendrites, unmyelinated axon, axon terminals, and terminal buttons
So, the section of the unmyelinated axon closest to the soma gets depolarized by the threshold potential. This area does this by opening its voltage-gated sodium ion channels to let in sodium ions. It also activates nearby sodium channels to depolarize those nearby areas. The first area will get repolarized and the other area is depolarized, activating nearby channels and the cycle continues down the axon. This is called a self-propagating wave.
The depolarization and repolarization of one area is called a local current
Oscilloscope uses electrodes to measure the membrane potentials
what is the difference with adenoviruses and retro viruses?
What is a bacteriophage? How does it look?
Adenoviruses: carry DNA and are non-enveloped
Retroviruses: carry RNA and are enveloped (HIV)
Bacteriophage: virus that can infect bacteria and archea (looks like that cool spider thing)
Describe how sodium potassium pumps work.
These are forms of active transportation. This returns the membrane potential back to resting potential (more negative environment inside the neuron)
- The pump opens inwards of the axon. This allows 3 sodium ions to get pumped through and bind to the binding sites
- ATP will turn into ADP and Pi which changes the shape of the pump allowing sodium to be released out of axon and allowing 2 potassium ions to bind to the binding site of pump.
- ATp will turn into ADP + Pi changing the shape of the pump again allowing potassium ions to be pumped inside the axon.
What is the difference with voltage gated sodium ion channels, voltage gated potassium ion channels, and sodium potassium pumps?
Voltage gated sodium channels use facilitated diffusion: pump sodium into the axon causing depolarization (positive neuron environment). This allows the neuron to reach its action potential.
Voltage gated potassium channels use facilitated diffusion: This pumps ions out of axon allowing for the repolarization of the neuron (becoming more of the negative neuron environment).
Sodium potassium pumps: use active transportation and maintain the resting potential of the neuron.
What are the different types of neurons
Sensory neuron (receptor to the brain)
Relay neuron (in the Central nervous system) brain to spinal chord
Motor neurons: spinal chord to an effector (gland or a muscle)
neuromuscular junction
what is a motor unit
neuromuscular junction: motor neurons attach to the muscles
–> neurotransmitter for muscle contractions is called acetylcholine
Motor: many axon terminals of the same neuron will attach to the multiple muscle fibers of the muscle so that there is a coordinated contraction of the entire muscle.
What is the skeleton used for?
Joints
Fulcrum
skeleton provides anchorage points for muscles and muscles pull on them to contract.
Joints are areas where one part of the muscle attaches to a fixed bone and the other part attaches to a moving bone. There is a pivot point called the fulcrum which allows the joint/ lever to move hence allowing muscle contractions
What is the synovial joint
What is the tissues that join bones, muscles, etc together?
draw the diagram and label
It is the area of the joint where there is synovial fluid for the joint to create a viscous environment and reduce friction
Tendons are a fibrous connective tissue that connects muscle to bone
Cartilage: made up of collagen (flexible connective tissue) that covers the ends of bones where the joint lies. This is so that when the muscle does contract and the joint moves, the bones will rub against each other with less friction
Ligaments: fibrous connective tissue (connects bones to bones) it also supports organs
What are the types of joints?
Hinge joints: less range of motion (flex and extending) (knees, elbows)
Ball and socket joints: wider range of motion ( hips, shoulders )
–> These are less stable hence you need stabilizing features like ligaments
What is locomotion? Why do animals need this?
What are some special locomotive adaptations of marine mammals?
locomotion: movement of entire organism from one place to another. Needed to hunt, evade predators, migrate, and find a mate
marine mammals:
- streamlined body shape (teardop shape) to reduce friction since water is more viscous than air
- Airway is through the blowhole, not the mouth so water doesn’t get into the lungs
- Flippers, fins, and tails to move in water
- blubber for buoyancy
How does the plasmodesmata work in phloem?
Between companion cells and sieve tube
In companion cells: hydrogen ions are pumped out of the cell and this causes the to return to the cell through co transport proteins while carrying sucrose. That sucrose will build up in concentration in companion cell and diffuse out through the plasmodesmata into the sieve tubes.
How does the heart respond to messages from the brain?
The medulla of the brain sends messages to the SA node (pacemaker) of the heart.
through the sympathetic nerve, it sends a neurotransmitter called norepinephrine increasing heart rate
Through the parasympathetic nerve , its sends acetylcholine to decrease heart rate
Brain to heart, it sends epinephrine neurotransmitters to increase heart rate before physical activity
Describe how the structure of cellulose and glycogen allow them to perform their functions
Cellulose: alternating beta glucose monomers
Horizontal cellulose polymers are attached to each other via hydrogen bonds meaning cellulose is extremely stable for structural purposes of the plant
Glycogen: made of 1-6 alpha glucose monomers and are highly branched allowing for more energy to be stored and extracted for animals.
