bio diversity of living things Flashcards

Question

Species Diversity

Answer 1

The variety and abundance of species in a given area Ex: a meadow with diverse species

Answer 2

viruses that infect and destroy bacterial cells (eaters of bacteria)

Answer 3

The current consensus among the scientific community is that the virus stays in the lysogenic cycle for 3-5 days before you begin to feel ill ● Reports say that the virus remains in the lysogenic cycle for 14 days before phasing into the lytic cycle ● The COVID-19 coronavirus mutation discovered on December 29, 2019 is allowing many of its hosts to roam about oblivious to their new attachment (asymptomatic) ○ This allows COVID-19 to acquire more and more hosts ● COVID-19 is a zoonotic virus meaning that another species of animal other than humans is where the virus genetically originated from (MERS in 2012 and SARS in 2003 were both zoonotic coronaviruses)

Answer 4

The theory that explains how eukaryotic cells evolved from the symbiotic relationship between two or more prokaryotic cells. RECALL: a symbiotic relationship is an interaction between two different organisms living close together that mutually benefit from each other The theory suggests that mitochondria and chloroplasts were once small, free-living prokaryotes Mitochondria → generates energy (ATP) for the cell Chloroplast → conduct photosynthesis They were engulfed by other, larger cells * They remained intact and continued to function, benefitting the cell Endosymbiont: a cell that is engulfed by another cell Host Cell: a cell that engulfs another cell Evidence: Similar features between chloroplasts, mitochondria, and prokaryotes: ❏ Membranes ❏ Circular Chromosomes ❏ Similar gene sequences ❏ Ribosomes were similar ❏ Divide by binary fission

Answer 5

Vaccine: contains an agent that resembles the virus and is made from weakened or killed forms of the virus, or its surface proteins Vaccines are thought to act as the initial exposure so that your immune cells could recognize and create an immune response (antibodies) against that particular virus This will strengthen your secondary immune response, so that when exposed the virus can be destroyed immediately As we are seeing in the world around us right now, there are different types of vaccines. DNA/RNA based vaccines (including mRNA) * Use pieces of genetic material that code for part of the virus * Your body can use this injected genetic material as instructions to start copying the virus antigen * Your body will recognize these instructions and will start creating an immune response ready to protect you if you encounter the virus → It is impossible to get the targeted virus from this type of vaccine → These vaccines can be quickly created based on genetic sequencing; however, if the virus mutates boosters may be required Examples: Pfizer and Moderna Covid-19 Vaccines Virus Vectors * Use a weakened form of the virus that is incapable of causing the disease itself * Your body will receive the virus antigen which will then trigger a strong immune response * These vaccines have been around longer than mRNA vaccines * Smallpox, Ebola, Zika, HIV, Influenza, Tuberculosis, etc. → Usually one single dose is enough to stimulate long-term protection, even if the virus mutates → In some cases the body could develop an immune response to the antigen instead of the virus, making it less effective Examples: AstraZeneca and Johnson & Johnson Covid-19 Vaccines

Answer 6

Darwin proposed the theory of natural selection based on: 1. All members of a species display inherited characteristics 2. The number of offspring produced by individuals in a species exceeds the number that will survive to adulthood 3. Some offspring, because of individual differences, are better able to adapt to environmental conditions than others 4. The better-adapted organisms pass on their characteristics to their offspring and the population changes If none adapt then the species will go extinct overtime* ________________________ Sexual reproduction provides opportunities for genetic variation within a species * Genetic variation is important in an unstable environment so that changes in conditions do not result in the extinction of a species due to an inability of individuals to adapt

Answer 7

Prions are non-viral diseases causing agents ● They are infectious particles that cause damage to nerve cells in the brain ● They are disease causing agents that lack RNA or DNA ○ Prions seem to behave like a virus but are not ● Disease results when prions change their molecular shape and become deadly Example: Creutzfeldt-Jakob Disease (CJD) → A fatal brain disorder → Symptoms include memory problems, poor coordination, behavioural changes, etc.

Answer 8

Eukaryotes have more reproductive diversity than prokaryotes ● Prokaryotes are unicellular organisms that usually divide asexually ● Eukaryotes can use more complicated methods of reproduction Binary Fission: the cell divides itself into two, equal, identical parts with the same DNA → Multiple Fission (Asexual Reproduction): making multiple copies of itself at the same time → Sexual Reproduction: gametes have half the chromosomes join to form a zygote with two sets of chromosomes

Answer 9

A cell that engulfs another cell

Answer 10

Hypothesis: first multicellular organisms arose from colonies created by dividing individual cells * Genes within these cells carried instructions to become specialized for different functions Example: some cell groups became specialized in absorbing nutrients, while others become specialized in gathering information from the surrounding environment

Answer 11

(Asexual Reproduction) making multiple copies of itself at the same time

Answer 12

gametes have half the chromosomes join to form a zygote with two sets of chromosomes

Answer 13

Viruses differ from both prokaryotic and eukaryotic cells ● They cannot sustain life outside of a host cell ○ Outside a cell viruses are dormant (inactive) ● They must invade cells and use the host cell’s internal machinery for survival and reproduction Viruses are nonliving because: 1) They cannot live independently outside of the host cell 2) They are not prokaryotic or eukaryotic cells because they lack cytoplasm, organelles, and cell membranes Viruses are small particles made up of a nucleic acid core & a protein coat (a capsid) * Viruses have either DNA or RNA (RNA is more susceptible to mutation) → Since there is genetic material, the viruses can exist within cells, make new copies & can spread to other cells * Their origin is unknown, but probably originated as genetic material that made its way outside of the cell & evolved a protein coat for protection ________________________ classifying viruses Normally scientists will classify viruses based on: 1) Size and shape 2) Types of diseases they cause 3) Genome (set of genes) and type of genetic material (DNA or RNA) 4) Method of reproduction DNA Viruses: tend to be less virulent & follow the Lytic Cycle of infection. The human immune system can detect & destroy DNA viruses therefore an organism will detect a DNA virus within a limited time frame ● DNA Virus Examples: chicken pox, shingles, warts RNA Viruses: (70% of viruses) can remain undetected in an organism for a long period of time & spread throughout the body. Follow the Lysogenic Cycle, splicing their viral DNA into the host’s DNA and could remain dormant for years. It isn’t until it is activated that the host immune system will detect it ● Will undergo mutation more frequently, giving more variants of the virus (some may be better at invading the host) ● RNA Virus Examples: Coronavirus, AIDs, rabies, measles ________________________ Viral reproduction: All viruses must undergo replication (copy the DNA) within the host cell ● Viruses do not have their own proteins to be able to carry out this process on their own ● The host cell can be either a prokaryote or a eukaryote depending on the type of virus ● The virus’ genetic material uses the host cell’s copying machinery to produce multiple copies of themselves (new viruses) ● Once the DNA is copied and made into proteins all of the individual components of the virus are assembled within the host cell Viruses have two possible reproduction pathways: The Lytic Cycle or The Lysogenic Cycle 1. The Lytic Cycle: DNA viruses deactivate the host mRNA & take control of the host’s machinery to make their own virus particles (potentially 1000 made). Once they are made, the new viruses destroy the host cell & are released to the neighbouring cells. Attachment: proteins on the surface of the virus bind to protein receptors on the surface of the host cell’s membrane. Entry: The virus injects its genetic material (DNA or RNA) into the bacterial cell. Replication: The host cell makes more viral DNA or RNA and proteins. Assembly: New viral particles are assembled. Lysis and Release: The host cell breaks open and releases new viral particles\ The Lysogenic Cycle: The virus enters and then attach their DNA to the host’s chromosomes. * When the viral DNA enters the host cell’s chromosome it may remain dormant (inactive) and later activate and instruct the host cell to produce more viruses through the lytic cycle. RNA viruses get access to the host cell and change the cell’s genetic material to its own → It is then replicated every time the host goes through mitosis → This lets it spread without being detected and destroyed by the host immune system → Once activated, it will follow the Lytic Cycle and can be detected by the organism; however, at this point too much damage has already been done Lytic Cycle Viruses: newly formed viruses burst from the host cell, usually killing it → In multicellular hosts these newly formed viruses infect neighbouring cells Result: damage to host varies Lysogenic Cycle Viruses: effects to the host might not be immediate → Some viruses may be dormant within the cell and only go through a lysogenic cycle for a prolonged period of time → The virus cannot be detected and no symptoms appear → The virus is able to spread into other cells through replication without actually killing the host cells ________________________ Since viruses can transfer their genetic material from one cell to another (both within and between different species) they are a great genetic engineering application ● Bacteria contain small segments of DNA in structures called PLASMIDS which can be used to splice a specific DNA sequence and put it into a plasmid, allowing it to replicate and generate many copies of the desired DNA sequence for future study

Answer 14

Lysogenic viruses can infect a host cell and stay dormant by incorporating their genetic material into the host DNA ● Retroviruses use the enzyme Reverse Transcriptase to turn their RNA into DNA, allowing them to add themself into the host genome ● When viral DNA becomes part of the host DNA it is called a provirus In a normal cell, DNA is transcribed into RNA and then RNA is translated into proteins. → When a retrovirus is inside of a cell, the first two steps of the process are switched. Rather than DNA -> RNA -> Proteins, it's RNA -> DNA ● Reverse transcription lacks the usual proofreading of DNA replication ● This allows the retrovirus to mutate often! 1. Retrovirus attaches to host cell and Viral RNA is copied into DNA by reverse transcriptase 2. The proviral strand will be integrated into the host’s DNA. 3. The DNA becomes transcribed and translated to produce more viruses without destroying the cell. 4. Every time the host divides, the proviral DNA is replicated along with host DNA