Bio Full Review

Name 5 structures that may be on a virus

Matrix, Envelope, Envelope Protein, Matrix, Capsid, DNA/RNA

What is one thing that all cells that which viruses do not have, and how does this affect them?

Viruses do not have cytoplasm, which means they do not have any metabolism (also, they have few enzymes)

Why are viruses not considered living thigns?

They cannot perform the 8 functions of life without relying on a host cell

What are the two different cycles that viruses go through to reproduce?

the lytic and lysogenic cycle

What enzyme is present in a retrovirus and what does it do?

Reverse transcryptase in retroviruses convert viral RNA to DNA that can be transcribed to make viral proteins

What are ways that the genetic material in a virus can differ?

RNA/DNA, double/single stand, positive/negative sense

What types of cells do enveloped viruses infect? Non-enveloped viruses?

Animal cells and bacterial/plant cellsHow

How do viruses form their envelopes?

They derive their membrane from the host cell’s phopholipids

Name the 7 steps of the Lytic Cycle

1. Attachment

2. DNA Entry

3. DNA Replication

4. DNA Transcription

5. Protein Synthesis

6. Lysis

7. Spread

Name the 5 steps of the Lysogenic Cycle

1. Attachment

2. DNA Entry

3. Integration

4. Cell Division

5. Stimuli causes the virus to begin the Lytic Cycle

What is a benefit of the lytic cycle?

Rapid rates of reproduction

What is a drawback of the lytic cycle/virulence?

If viruses are able to avoid detection from the host’s immune system and cannot be destroyed, it may eventually kill all host cells and not be able to survive. This is a drawback unless the virus is able to spread to a different host.

What are 2 benefits (one to the host, one to the virus) of the lysogenic cycle?

1. During integration, a virus may transfer genes from a previous host into the new host’s DNA, which increases genetic diversity and promotes evolution.

2. The virus remains in a temperate state and spreads rapidly to new daughter cells without being detected

What is a drawback of the lysogenic cycle?

Slower rates of reproduction

What evidence suggests that viruses came from multiple ancestors?

Their structures are highly different, the ones that seem to match likely come from convergent evolution

What evidence suggests that viruses came before cells?

They have a simpler structure

What two hypotheses suggest that cells came before viruses?

Progressive and Regressive hypotheses

What does the Progressive Hypothesis suggest?

Viruses were built by a series of steps by modifying previous cell component. The evidence supporting this is that retrotransposon nucleotides in cells behave very similarly to how viruses integrate viral DNA into host DNA, suggesting viruses may have evolved from them.

What does the Regressive Hypothesis suggest?

Viruses develop from cells in a series of steps caused by a loss of cell components. The evidence supporting this is that there are parasitic bacteria like Chlamydia that have lost life functions after relying on host cells, suggesting that viruses may have evolved from intraparasitic bacteria like such.

What are 3 reasons for why evolution in viruses is so rapid?

1. Viruses have short generation times (24hrs)

2. High mutation rates cause more genetic variation and are high in viruses due to a lack of proofreading (especially RNA viruses)

3. Large amount of natural selection allow viruses to evolve because hosts have developed many ways to fend off viruses

What are two examples of rapidly evolving viruses?

Influenza Virus and HIV (Human Immunodeficiency Virus)

For Bacteriophage Lambda:

1. What type of virus is this?

2. Is it enveloped or not enveloped?

3. What kind of genetic material does it have?

4. What kind of cells does it infect?

1. Bacteriophage

2. Non-enveloped

3. 1 Double-stranded DNA molecule

   1. Bacterial cells (Escherichia coli)

For COVID-19:

1. What type of virus is this?

2. Is it enveloped or not enveloped?

3. What kind of genetic material does it have?

4. What kind of cells does it infect?

1. Coronavirus

2. Enveloped

3. 1 Single-stranded RNA molecule

4. Human Cells (lungs)

For HIV (Human Immunodeficiency Virus):

1. What type of virus is this?

2. Is it enveloped or not enveloped?

3. What kind of genetic material does it have?

4. What kind of cells does it infect?

1. Retrovirus

2. Enveloped

3. 2 Copies of a Single-stranded RNA molecule

4. Human T-Helper Cells (white blood cells)

What are two reasons why HIV is the fastest evolving virus?

High mutation rate caused by a lack of proofreading and the potential to mutate from cytidine deaminase, which is necessary to convert cytosine to uracil for RNA

What are the three parts of Cell Theory?

1. All living things are cells

2. Cells are the smallest unit of life

3. Cells come from pre-existing cells

What type of reasoning (inductive/deductive) was used to CREATE the Cell Theory?

Inductive Reasoning - Using specific data to come to a general conclusion about all cells

What type of reasoning (inductive/deductive) is used to PREDICT NEW INFORMATION using the Cell Theory?

Deductive Reasoning - Using the general conclusion of the cell theory to predict specific information about the cells of new organisms

How do Striated Muscle Fibers challenge the cell theory?

They are very large and are multi-nucleated because they are a fusion of multiple stem cells

How do Red Blood Cells challenge the cell theory?

They have no nuclei and do not make new cells - but they are still cells because they come from pre-existing cells.

How do Aseptate Fungal Hyphae (no cell walls) challenge the cell theory?

They are multi-nucleated, but still come from pre-existing cells

How do Phloem Sieve Tube Elements challenge the cell theory?

They have no nuclei or organelles, but still come from pre-existing cells

According to IB, what are the eight functions of life?

Nutrition, Metabolism, Growth, Response to Stimuli, Movement, Excretion, Homeostasis, Reproduction

What are Emergent Properties?

New functions that are produced when multiple individual components interact with each other - i.e. Multicellularity

What must be MINIMIZED to optimize cell transportation?

Volume

What must be MAXIMIZED to optimize exchanges (heat, waste, nutrients) between cells?

Surface Area

What are 2 examples of structures that have adapted in order to have better Surface Area-to-Volume ratios?

Microvilli, Erythrocytes (red blood cells w/divots)

What is the metabolism of a cell?

The chemical reactions occurring in the cytoplasm

What is a cell’s metabolic rate proportional to?

Volume

What changes the rate at which a molecule is able to cross the plasma membrane?

Surface Area

How does Cell Differentiation occur?

When different genes are expressed/not expressed in order to create specific proteins

What is a characteristic of cells in a multicellular organism?

They cannot live independently outside of the organisms

What are 2 benefits of multicellularity?

1. Organisms have a longer lifespan because cell deaths are negligible

2. Organisms have increased complexity, allowing them to thrive in niches and adapt better

How do unspecialized cells differentiate into specialized cells?

The way cells differentiate depends on the position of the cell in its embryo, which is indicated using gradients of signaling chemicals

What are 2 characteristics of stem cells that make them useful?

1. They can divide repeatedly

2. They can differentiate into many types of cells

What is a stem cell niche?

The precise location of stem cells in a tissue that allow them to remain inactive for a long time - i.e. Bone Marrow and Hair

What are totipotent cells?

Early stage embryo cells that can differentiate into any cell type

What are pluripotent cells?

Cells during embryo development that gradually commit to a pathway of differentiation, but can still differentiate into a range of cell types

What are multipotent cells?

Cells in adult tissue that can only differentiate into cells of specific cell types - i.e. Bone Marrow

What is the Magnification Formula?

Magnification = Measured Size of Scale Bar / Actual Size of Scale Bar

What is the formula for finding the Actual Size of a structure?

Actual Size = Measured Size of Structure / Magnification

What are 4 structures found in ALL cells?

DNA, Ribosomes, Cytoplasm, Cell Membrane

What are 4 characteristics of Prokaryotes?

No membrane bound organelles, no nucleus, uncoiled DNA with no histones, smaller 70s ribosomes

What are 4 characteristics of Eukaryotes?

Membrane bound organelles, nucleus, DNA coiled using histones, larger 80s ribosomes

What structures should be included in a prokaryote cell drawing?

One strand of uncoiled DNA, 70s ribosomes in cytoplasm, cell wall and plasma membrane, nucleoid, pili

What structures should be included in a plant cell drawing?

Nucleus, large central vacuole, sap vacuoles, cell wall and plasma membrane, chloroplast, mitochondria, 80s ribosomes in cytoplasm, RER by nucleus, SER, Golgi Apparatus

What structures should be included in an animal cell drawing?

Nucleus, vacuoles, plasma membrane, mitochondria, 80s ribosomes in cytoplasm, RER by nucleus, SER, Golgi Apparatus, lysosome, microvilli, vesicles by golgi

What is the difference between the cell walls of plants and fungi?

Made of cellulose vs. made of chitin

What is the difference between the cytoplasm of prokaryotes and eukaryotes?

uncompartmentalized vs. compartmentalized

What are Scanning Electron Microscopes?

Electron microscopes that bounce electrons off cell surfaces to create 3D images of them

What are Transmission Electron Microscopes?

Electron microscopes that transmit electrons through samples to see their ultrastructure

What is Immunofluorescence?

Allows cells to be identified under light microscopes by using antibodies that bind to different antigens on cell structures

What is Freeze Fracture Electron Microscopy?

Produces images of surfaces WITHIN cells by freezing then fracturing them at weak points

What is Cryogenic Electron Microscopy?

Freezes protein structures to study them at points of change

What does it mean for phospholipids to be amphipathic?

They have both polar and non-polar regions due to their hydrophobic heads and hydrophilic tails

What does cholesterol do in the plasma membrane?

It regulates membrane fluidity by preventing stiffness in cold temperatures and runniness in hot temperatures

What is the name of the carbohydrate attached to a glycoprotein?

Oligosaccharide

What do glycoproteins do in the plasma membrane?

Used for cell adhesion and recognition

What do cell adhesion molecules (CAMs) do?

Connects cells tightly to form tissues

What is the name of the model for plasma membranes?

Fluid Mosaic Model

What are 2 characteristics of passive transport?

Substances move from high to low concentration, and it requires no ATP

What are 2 characteristics of active transport?

Substances move from low to high concentration, and it requires ATP

What is cotransport?

Combines active pumping and facilitated diffusion

What is exocytosis?

The process of molecules exiting a cell using vesicles

What is endocytosis?

The process of molecules entering a cell using vesicles

What does it mean for a solution to be Hypertonic?

It has a higher solute concentration relative to another substance

What does it mean for a solution to be Hypotonic?

It has a lower solute concentration relative to another substance

What does it mean for a solution to be Isotonic?

It has an equal solute concentration relative to another substance

How does cytokinesis occur in animal cells?

Contractile proteins (actin, myosin) pull the cell membrane inwards around the cell equator, creating a cleavage furrow that is pinched to split one cell’s cytoplasm into two daughter cells

How does cytokinesis occur in plant cells? (4 steps)

1. Microtubules are built as scaffolding for vesicles to form at the cell’s equator.

2. The vesicles fuse to form a cell plate that grows until it connects to the plasma membrane and forms a double membrane

3. The middle lamella is formed when vesicles deposit substances in between the double membrane at the equator by exocytosis

4. Cellulose is deposited near the middle lamella to form two new cell walls for both daughter cells, dividing their cytoplasm.

What do you call the plasma membrane channels that allow for communication/transport between plant cells?

Plasmodesmata

What is an example of equal cytokinesis?

Root growth

Describe how Oogenesis is an example of unequal cytoplasm

To create oocytes, the first meiotic division creates one large cell with most of the cell’s cytoplasm and a smaller polar body that does not keep developing.

Describe how Yeast Budding is an example of unequal cytokinesis

Yeast reproduces asexually by budding, where the daughter cell receives a nucleus after nuclear division but less cytoplasm than the parent cell had

How do the purposes of meiosis and mitosis differ?

Meiosis allows for genetic diversity and therefore evolution, while mitosis allows for reliable cell growth and repair

What is different about the number of chromosomes in human meiotic daughter cells and human mitotic daughter cells?

Haploid (23 chromosomes) vs. Diploid (46 chromosomes)

What is a genome?

The entire set of DNA instructions for an organism (for humans, 46 chromosomes aka 23 chromosome pairs)

What are sister chromatids and what protein are they held together by?

Two strands of a chromosome held together by cohesin that each contain the same copy of the original chromosome

What are the four phases of mitosis?

Prophase, Metaphase, Anaphase, Telophase

What occurs during interphase?

DNA is replicated and the cell size is doubling in preparation for mitosis

What occurs during Prophase?

Chromosomes are condensing and microtubules are growing. At the end of prophase, the nuclear membrane is completely dissolved.

What occurs during Metaphase?

Chromosomes are aligned at the cell equator and microtubules attach to the centromeres of chromatids.

What occurs during Anaphase?

Cohesin connecting sister chromatids are cut so that kinetochores on their centromeres can shorten microtubules to pull each chromatid towards opposite poles. Chromatids are now separate chromosomes.

What occurs during Telophase?

Cytokinesis and the decondensing of chromosomes. A new nuclear membrane is formed for each group of chromosomes at different poles.

How does cell division occur for prokaryotic cells?

through Binary Fission - one circular chromosome is copied and then the cell grows and divides

What are the cell cycle phases in order?

G₁, G₀ (occasionally), S, G₂, M,

What occurs during G₁?

Protein Synthesis, Cell Growth

What occurs during G₀?

Long term interphase for cells or regular cell maintenance for cells that do not divide

What occurs during S phase?

DNA Synthesis/Replication

What occurs during G₂?

Cell Growth