Chapter 7: Cell Structure & Function Flashcards
Robert Hooke
- 1st person to describe cells
- observed cork (plant cells) with a microscope
Anton Van Leeuwenhoek
first to observe:
- protists in pond scum
- blood cells, bacterial cells, yeast cells
- Conclusion: cells are the basic unit of life!
Matthias Schleiden
- Studied plant cells
- concluded that all plant parts are made of cells
Theodor Schwann
- studied animal cells
- concluded all animal tissues were made of cells
Rudolf Virchow
- concluded that cells only form from other cells
What 3 things to does the cell theory state?
- living things are composed of cells
- cells are the basic unit of life
- new cells are produced from pre-existing cells
How does a light microscope function?
- light passes through a specimen
- two lenses form an image
limitations of a light microscope
- magnifies 1000x
- cells are transparent (dyes/stains are required)
How does an electron microscope work?
- beams of electrons focused by magnetic fields
- reveals details 1000x smaller than light microscope
limitations of an electron microscope
- can only visualize nonliving, preserved cells and tissues
All cells have a cell membrane. T or F
True
What are the two layers of phospholipids called?
Lipid bilayer
What are the two lipid bilayers?
- Phosphate heads (polar)
- Fatty acid tails (non-polar)
- proteins, carbohydrates, cholesterol in membrane
What are the two types of cellular transport?
passive transport & active transport
Passive transport
-
doesn’t use energy
1. diffusion
2. facilitated diffusion
3. osmosis
Active transport
- cell uses energy
1. protein pumps
2. endocytosis
3. exocytosis
What is the energy used in cellular transport?
ATP
PASSIVE TRANSPORT
- movement of molecules from one side of the membrane to the other
- NO additional energy added
- maintains balance in the cell (homeostasis)
- moves down concentration gradient (high -> low)
Concentration gradient is what?
the concentration difference between regions of high/low concentration.
Diffusion
the movement of solute particles from high -> low concentration.
Facilitated diffusion
- Using proteins as channels to pass certain molecules to the membrane. (transport proteins/protein channels)
- used to transport large, charged, or water molecules.
- example = glucose molecules
Osmosis
- Diffusion of water through the membrane using aquaporins
- Movement of water through cell membranes to side with LESS concentration
What are aquaporins?
Transport proteins that allow water to pass through the membrane
Why do water molecules have a tough time passing through the cell membrane?
- its polarity
- the unstable negative and positive charges causes a tough time for water molecules to pass through the transport proteins and across towards the cell membrane.
Isotonic
Same concentration on both sides (outside/inside the cell)
Hypertonic
More solutes than water molecules (concentrated)
Hypotonic
More water molecules than solutes (diluted/not concentrated)
What are some cells that can be seen without a microscope?
- Amoeba (0.5mm)
- human egg cell
- chicken egg
Cytoplasm
- Fluid inside cells
- Holds organelles in place
Prokaryote (bacteria)
- small and simple
- NO nucleus
- cell membrane & cytoplasm
- ribosomes
- grow, reproduce, respond to change
- may use flagella/cilia for movement
- may have cell wall
Eukaryotes
- vary in shape
- highly specialized
- have a nucleus and membrane-bound organelles
- cell membrane and cytoplasm
- DNA in the nucleus
- multicellular/unicellular
Nucleus
- only in eukaryotic cells
- control cell processes
- stores DNA
- codes for new proteins
Binucleate/Multinucleate Cells
- cells with more than one nucleus
- skeletal muscle cells, heart cells, and some liver cells
- reason: they have many functions and thus need multiple nuclei to carry out these tasks
Nuclear envelope
- surrounds nucleus
- double membrane layer
- pores allow material to move in/out of the nucleus
Chromatin
- in the nucleus
- string of DNA
- condenses to form chromosomes during cell division
Chromosome
- Strings of chromatin formed and joined together make a chromosome (condensed chromatin)
- compacted DNA
- pass genetic info to following generations
Nucleolus
- dark spherical mass inside nucleus
- assembly of ribosomes
Cytoplasm
- Gel-like substance within membrane and nucleus
- holds organelles
- transports materials used for cell activites
Cytoskeleton
- nucleus to cell membrane
- protein filaments (microtubles, intermediate filaments, microfilaments)
- maintain shape/support
- cell movement
Cilia
Many short-like projections
Flagella
One or two longer whip-like structures
Centriole
- Animal cells
- outside nuclear envelope
- help separate chromosomes during cell division
Endoplasmic Reticulum
- transports materials
Rough ER
- ribosomes
- protein sysnthesis
Smooth ER
- no ribosomes
- creates lipids and detoxifies cell
Ribosome
- In the nucleus, cytoplasm, and Rough ER
- produce proteins based on instructions from DNA
Golgi Apparatus
- near ER and nucleus
- further packages and modifies proteins after ER
- proteins sent outside of the cell or to organelles
Protein Assembly
- Proteins are assembled on ribosomes
- Proteins targeted for export to the cell membrane, or to specialized locations within the cell, complete their assembly of ribosomes bound to the rough ER.
- Newly assembled proteins are carried from the rough ER.
Lysosome
- cytoplasm, rare in plant cells
- contain enzymes that break down food into nutrients for cell
- also a “cell cleaner”, breaks down old organelles
Central Vacuole
- plant cells only
- cytoplasm
- stores water & nutrients
- pressure in plant vacuole aid in support of plant cell
Vacuoles
- cytoplasm
- in animal cells, protists
- small saclike structures
- store nutrients, remove excess water from the cell
Chloroplasts
- in cytoplasm of plants, some protists, & bacteria
- photosynthesis; uses energy from sunlight to produce glucose
Mitochondria
- Cytoplasm, more in muscle cells
- POWERPLANT
- cellular respiration; generates cellular energy (ATP) from glucose
Cell wall
- outermost boundary in plant, bacteria, and fungi cells
- support and protection, maintain cell shape
Cell membrane
- outer boundary of cells
- semipermeable
- controls what enters and exits the cell to maintain an internal balance called homeostasis. (semipermeable)
- provides protection and support for the cell
- cell communication
What does the cell membrane contain?
Lipid bilayer: containing proteins and carbohydrates
What are membranes made out of?
PHOSPHOLPIDS
- lipid bilayer (doube layer)
- hydrophobic fatty tails inside
- hydrophilic heads outwards to water
Fluid Mosaic Model
- Membranes embedded with proteins & carbs
- can move around and “float” among lipids
- proteins form channels and pumps that help to move material across cell membrane
Osmotic pressure
- movement of water out of or into a cell exerting a force.
- for organisms to survive, they must have a way to balance the intake and loss of water
The size of the image formed by a light microscope is limited. True or False?
TRUE
Fluorescent dyes help scientists see the movement of compounds and structures in living cells. True or False?
TRUE
Transmission electron microscopes form a 3-d image of the surface of the specimen. true or false?
FALSE; scanning electron microscope
A scanning electron microscope (SEM) image is formed by ______.
beams of electrons being scanned
What does the term “organelle” literally mean?
little organs
How are contractile vacuoles different from other types of vacuoles?
Contractile vacuoles help with the maintenance of osmotic pressure in the fluids of organism by balancing the concentrations of water and solutions.
What structure of cytoskeleton is found in animal cells but not plant cells?
centrioles
Chloroplasts and mitochondria are surrounded by a double membrane. True or False?
True
Nearly all of the mitochondria in your cells were inherited from your father. True or False?
False; mother
Both chloroplasts and mitochondria lack genetic information. True or False?
False; they contain genetic information
Most _____ are porous to water and other materials but strong enough to support and protect cells.
Cell wall
Nearly all of the plant tissue called ____ is made up of cell walls.
wood
How to the function of vesicles help in the synsthesis of proteins and the release of proteins?
Vesicles transport items to the golgi apparatus, which modifies proteins. After, the vesicles transport these to the cell membrane where they can be released.
What are some examples of osmotic pressure?
- plasma surrounds red blood cells
- water and nutrients enter plant cells thru osmosis.
- when a wilted plant is watered, osmosis makes the plant firm again.
Exocytosis
fusion of vesicle to membrane for release
Endocytosis
the cell takes in macromolecules by forming vesicles from the plasma membrane
What are the 3 types of endocytosis?
Phagocytosis, pinocytosis, receptor-meditated endocytosis
ACTIVE TRANSPORT
- movement from low concentration to high
- certain molecules/ions need transport proteins called “protein pumps” to cross the membrane. (ex: calcium, potassium, sodium ions)
True or False; active transport uses channel proteins.
FALSE; protein pumps
Phagocytosis = cell _____
EATING
Pinocytosis = cell _______
DRINKING
How does a hypotonic solution look in an animal and plant cell?
Animal: lysed
Plant: turgid (normal)
How does an isotomic solution look in an animal/plant cell?
Animal: Normal
Plant: flaccid
How does a hypertonic solution look in an animal/plant solution?
Animal: Shriveled
Plant: Playsmolyzed
Endocytosis is a ______ of exocytosis, involving different _______.
reverse, proteins
ENDOCYTOSIS (detail)
Taking bulky material into a cell
- uses energy
- cell membrane in-folds around food particle, forms food vacuole & digests food
- how white blood cells eat bacteria
EXOCYTOSIS (detail)
cells releasing large amounts of material from the cell
- the membrane of vacuole surrounding the material fuses with cell membrane, causing contents out of the cell
Receptor-mediated endocytosis
Binding of ligands to receptors triggers vesicle formation
ligand
any molecule that binds specifically to a receptor site of another molecule
Cellular membranes are fluid mosaics of lipids and proteins.
- phospholipid bilayer
- integral proteins
- peripheral proteins
- cholesteral
- carbohydrates
Integral proteins
- COMPLETELY embedded in the membrane; “big protein”
Peripheral proteins
- LOOSELY bound to the membrane surface like a “small protein on the side”
Cholesterol
regulates membrane movement during temperature changes, attached between phospholipids
- membrane fluidity
Carbohydrates
Attached to the membrane and membrane-bound proteins
- glycolipids (phospholipids + carbohydrate)
- glycoproteins (protein + carbohydrate)
