HL Biology Unit 1.1-1.6

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 cell 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 cytoplasm

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

What occurs during M phase?

Mitosis

What are cyclins?

A family of proteins that control cell cycle progression by binding with and activating enzymes to modify proteins

What are mutagens?

Agents (ex. chemicals or radiation) that increase mutation rates

What are Proto-oncogenes?

Sections of DNA that control cell cycles and cell proliferation, who have the potential to cause cancer when mutated

What are Tumor Suppressor Genes?

Genes that inhibit cell proliferation by acting as cell cycle checkpoints and by controlling apoptis

What is apoptis?

Programmed cell death

What theory about cell behavior did Louis Pasteur disprove?

Spontaneous Generation - the theory that organisms can come from nonliving matter

Describe Louis Pasteur’s experiment

Using swan neck flasks filled with broth, Pasteur found that when sterilized, the broth would not decompose if microbes were not reintroduced to it (when they were stuck in the neck of the flask or the flasks were sealed to prevent entrance). This prove that cells come from other cells.

What is the theory of how life originated?

Abiogenesis - How life came from nonliving material

What is the 1st step of Abiogenesis?

The production of simple carbon compounds - amino acids are created from reactions in the Earth’s primordial soup with the compounds of Earth’s early atmosphere

How does the Miller-Urey experiment support the 1st step of Abiogenesis?

Simulated lightning caused reactions between water vapor and gases that would have been present in Earth’s early atmosphere, creating amino acids in the resulting recondensed liquid.

What is the 2nd step of Abiogenesis?

The assembly of carbon compounds into polymers - amino acids (monomers) combine to form proteins (polymers) near deep sea vents that provide heat

What is the 3rd step of Abiogenesis?

The formation of membranes - they just showed up somehow

What is the 4th step of Abiogenesis?

The development of a mechanism of inheritance - first came RNA, which then evolved into DNA

What is Endosymbiosis?

The relationship that describes one organism living inside another organism. This is the origin of Eukaryotes and organelles like chloroplast and mitochondria.

Why do we believe mitochondria and chloroplast evolved from being simple prokaryotic bacteria?

They have their own 70s ribosomes and single strange circular DNA like prokaryotes do

How many centimeters (cm) in 1 meter (m)?

100cm

How many millimeters (mm) in 1 centimeter (cm)?

10mm

How many micrometers (μm) in 1 millimeter?

1000μm