Bio - Cells Flashcards
What six things make up a living organism?
- Need energy
- Produce waste
- Respond and adapt to environment
- Reproduce
- Grow
- Made up of cells
Explain cell theory
- All organisms are composed of 1 or more cells
- Cell is the smallest functional unit of life
- All cells are produced from other cells
What is abiogenesis? How long was this theory accepted for?
Abiogenesis is the theory that life could arise from non-living matter. It was widely accepted for over 2000 years.
What is biogenesis?
Biogenesis is the theory that life could arise only from other living organisms.
Describe the composition of the cell membrane
- Composed of a double layer of phospholipids
- Proteins, lipids, and carbohydrates are embedded between the layers
What are the two main functions of a cell membrane?
- Biological barrier to prevent some substances from entering the cell in any way and surround each organelle to prevent unwanted chemical reactions.
- Selective filter to allow some, but not all, materials to cross.
What properties does a cell membrane have?
- All material entering & exiting the cell must cross the cell membrane
- Can change according to the cell’s needs
- Fluid and flexible, “fluid-mosaic” model
What is the phospholipid bilayer? What is it made out of?
Phospholipids:
- Each molecule has a head and a tail-
Heads are hydrophilic (water loving), dissolves in water, polar
Tails are hydrophobic (water fearing), H2O molecules push away tail, not polar
- Heads face out, tails are sandwiched between
- Two layers (bilayer)
What does Brownian motion state?
“In liquid or air, particles are in a constant, random motion.”
What is a concentration gradient? Which way are you moving if molecules go from a high concentration to a low concentration? How about a low conecntration to a high concentration?
Concentration Gradient:
Difference in concentration
High concentration to low concentration moving down
Low concentration to high concentration moving up
What is equilibrium? What 3(ish) things happen?
Equilibrium:
- Molecules are evenly distributed on either side of cell membrane
- Overall (net) flow does not change
- Do not stop moving after reaching balance
What are three ways molecules can be transported across the cell membrane in order to reach equilibrium?
- Passive transport (Diffusion, osmosis, facilitated diffusion)
- Active Transport
- Endo- and exocytosis
What is passive transport? What is it used for? What types are there?
- Does not require energy to move across membrane
- Used for molecules too large to pass through membrane or charged particles
Types:
- Diffusion - movement of particles from high to low
- Osmosis - movement of water molecules from high to low // Less solute, more water. More solute, less water //
- Facilitated diffusion -
- Carrier proteins - change shape to allow certain molecules (ie. sugar) to pass
- Channel proteins - charged ions in and out of cell (ie. Na+), must be opened
What is active transport? What is it used for?
- Requires energy (ATP) from cell to move particles from low concentration to high concentration
(against concentration gradient)
- Transport proteins bind to materials & change shape to move across membrane
Used by:
- Plant root cells to take in minerals from soil
- Remove waste in cells
What is endocytosis? When is it used? What direction does it go? What types are there?
- Membrane folds in, forms a pocket that turns into vesicle for transport
- Used when molecules cannot be moved by passive or active transport
- Into the cell
Types:
- Phagocytosis: “cell-eating”, ingest food/other solid materials
- Pinocytosis: “cell-drinking” ingest droplets of water/other fluids
- Receptor-mediated endocytosis: take in molecules (ie cholosterol), receptor on cell identies item and binds it to trigger endoycytosis
What is exocytosis? What is it used for? What direction does it go?
- Allows materials stored in vesicles/vacuoles to exit cell
- Used to release waste
- Out of the cell
What happens when the size of a cell increases?
Size increases, surface area to volume ratio decrease.
Why is a large volume bad?
- More energy is used to trasport materials through the cell because they have to go farther
- If the surface area is smaller than the volume, all parts of the cell won’t get nutrients they need
What surface area to volume ratio does the cell want?
The cell wants a high surface area to volume ratio because:
- The cell can get more nutrients & O2
- It is easier ot exchange food, waste, O2 and CO2 with their surroundings
Large surface area to volume ratio is better!
What is a hypotonic solution?
More water molecules and less solute particles in comparison to a cell
What is a hypertonic solution?
Less water molecules and more solute particles
What is a isotonic solution?
- Concentration outside and inside the cell is equal
- Rate that water flows into the cell & out of the cell is the same
Define lysis (+provide an example)
Cells gain so much water that they burst
ie. Animal cells cannot reach equilibrium in distilled water, water is flowing in at too fast of a rate
Define crenation (+provide an example)
Cells lose so much water that they shrink/shrivel up then die
ie. Animal cells cannot reach equilibrium in strong salt water, water is flowing out to balance at a too fast of a rate
Do cells stop growing?
Cells will only grow to a certain size then stop, it takes too much energy to support a huge cell.
Who first tested abiogenesis?
Francisco Redi used experiments to test this theory using meat in two jars & one covered.
What is the nucleus? What is its function?
The nucleus is the most visible part on the animal cell, its function is to control the cell’s activities.
What is encoded in the nucleus?
The cell’s genes (DNA) is encoded in the nucleus
How do messenger molecules exit the nucleus? What happens once they’re out?
Through the nuclear pores in the nucleus. The messenger molecules then attach themselves to ribosomes, which translate the information into proteins.
What organelles are only in plants? Explain their functions
Cell Wall:
- Made out of cellulose, rigid and supportive
Chloroplasts:
- Organelles of photosynthesis
- Have two layers of membranes: inner layer of flattened sacs & second layer encloses it
- Inner membrane includes cholrophyll: absorbs Sun energy and converts into chemical energy that creates sugars from CO2 and H2O
Explain the development of the cell theory
Robert Hooke:
- observed dead cork cells
- came up with word “cells”
Antony van Leeuwenhoek:
- 1st microscope
- studied blood cells, pond water, matter scraped from teeth
Schleiden and Swann:
- 1st to see nuclei in plant cells & animal tissue
Rudolf Virchow:
- cells divide to produce more cells
What is cancer?
Cancer is the damage to cells, which change DNA causing mutations
What is a virus?
A virus is genetic material inside a protein coat, however they cannot replicate themselves. They infect by taking over host (living) cells.
What do viruses and prions have in common?
They do not have independent life functions, therefore not considered functional units of life
What is a prion?
A prion is a protein that converts from its normal form into a harmful particle.
What is the endoplasmic recticulum?
Network of folded membranes and tubes connected with the nucleus, includes two types:
Rough Endoplasmic Recticulum:
- Has ribosomes, proteins created by them are packaged into vesicles.
Smooth Endoplasmic Recticulum:
- No ribosomes
- Combine lipids and packages proteins/lipids into vesicles
What is the golgi apparatus? What does it do?
- Molecules from endoplasmic recticulum are modified by enzymes
- Sorts and repackages molecules into vesicles
- Produces lysosomes
What does mitochondria do?
- “Powerhouse” of the cell
- Chemical reactions convert energy from food molecules into energy the cell can use
- Reactions happen on folded membranes inside the mitochondria
What do vacuoles do? What is the difference between vacuoles in plants and vacuoles in animals?
- Store water, food, minerals, and waste
- Plants have a large central vacuole to regulate water in the cell
- Animals have many smaller vacuoles
What are stem cells?
Stem cels are “blank slate” cells:
- divide to produce any type of cell in the body
- may hold the cure for many diseases.
What organelles are only in animals?
Lysosomes:
- Break down particles with digestive enzymes
- Can fuse with vesicles
Centrioles:
- Cylindrical structures outside nucleus
- Crucial during cell division, move correct genetic material into each new cell.
What is cytoplasm? What is it made out of?
Cytoplasm
- Jelly-like substance that fills cell & suspends contents
- Made up of +50% water
Name & contrast the organelles of a plant and animal cell
Organelles in both:
Cell membrane, nucleus, endoplasmic recticulum, golgi apparatus, mitochondria, vacuoles
Plants:
Cell wall and cholorplats
Animals:
Lysosomes and centiroles
