1st Midterm Flashcards
(28 cards)
A person is lost in the desert. (S)he has no water and after a couple of days loses so much
water through perspiration that his body fluids become hypertonic. What happens to his cells?
What happens to his proteins? What happens to his carbohydrates?
Cells will shrink due to water leaving the cell via osmosis, as the extracellular fluid now has a higher solute concentration, drawing water out of the cell
Proteins may begin to misfold, and protein denaturation and loss of enzymatic activity
The body uses stored carbohydrates (glycogen) for energy,
Why does life use carbohydrates as signaling molecules, and proteins as enzymes?
Carbohydrates work as signaling molecules because their diverse sugar arrangements allow for highly specific cell recognition patterns.
Proteins function as enzymes due to their complex structure with various amino acid side chains that enable precise catalytic activity for specific chemical reactions within the cell.
Fire eats, grows, moves, has children! Why isn’t it alive?!!
Fire lacks cells, metabolism, or DNA
What is the cell theory?
Cell theory states that all living organisms are composed of one or more cells, that cells are the basic unit of life, and that all cells come from pre-existing cells
What is the fluid mosaic model of the membrane?
the fluid mosaic describes a membrane as flexible, fluid bilayer of phospholipids with various proteins, where both lipids and proteins can move laterally within the membrane allowing for dynamic interactions and functions within the cell.
Could a cell survive by having just peripheral proteins on it’s membrane? Why?
No, a cell could not survive just by peripheral proteins since they can not perform essential functions like transporting nutrients, regulating ion flow, or acting as receptors.
Why do the phospholipids in the membrane form a bilayer?
because they both have a hydrophilic phosphate head and hydrophobic fatty acid tail
List and explain the ways cells can introduce fluidity /rigidity in their membranes. Why do they
do this?
Cells can introduce fluidity in their membranes by:
Increasing the proportion of unsaturated fatty acids in their phospholipids
What is homeostasis?
The body’s asbility to maintain a stable internal environment, or balance, despite external changes.
What are the different methods for transporting materials into and out of a cell?
There are two methods:
1. Passive Transport where: Diffusion, facilitated Diffusion, and Osmosis occur.
2. Active Transport where: Endocytosis and Exocytosis occur.
We are homo sapiens sapiens. What does this mean (think classification)
Homo sapiens sapiens is our scientific name based on biological classification (taxonomy).
Homo – This is our genus
sapiens – This is our species
sapiens (second one) – This indicates our subspecies
Know atomic structure, covalent bonds, peptide bonds, etc…
protons (positive), neutrons (neutral), and electrons (negative).
protons determine the element
electrons determine how atoms bond
Covalent bonds form when atoms share electrons to achieve stability
Peptide bond is a special type of covalent bond that links amino acids together to form proteins.
ionic bond forms when one atom transfers electrons to another, creating charged particles called ions
How do we study cells?
We visualize cells with the help of a microscope
What is a prokaryote? What structures does it have?
A single-celled organism that lacks a nucleus and other membrane-bound organelles.
Its DNA is floating in the cytoplasm in a region called the nucleoid
Structure:
Cell membrane, cell wall, cytoplasm, ribosomes, and a single circular chromosome in the nucleoid.
Can Bacteria carry out phagocytosis? Explain:
No, bacteria cannot carry out phagocytosis, since this process is primarily associated with eukaryotic cells!
What is a nucleus? An organelle?
A nucleus is a membrane-bound organelle found within a cell primarily responsible for storing and protecting the cell’s DNA in the form of chromosomes
An organelle is a subcellular structure that has one or more specific jobs to perform in the cell, just like an organ does in the body.
What are ribosomes?
Organelles that synthesize proteins in cells, they are made of RNA and protein
What are the five kingdoms of life? What basis is used for that organization? How about the 3 domains?
The 3 Domains:
1. Bacteria
2. Archaea
3. Eukarya (just not monera)
Five Kingdoms:
1. Animalia
2. Plantae
3. Fungi
4. Protista
5. Monera (Bacteria)
These are organized primarily based on nutrition, cell structure, and complexity of body organization.
How are pili and flagella different in bacteria?
Flagella are primarily used for movement by bacteria, while pili are primarily used for adhesion to surfaces or walls
What are polymers and monomers? Give examples:
A polymer is a chain of many monomers linked together like proteins (polymer) made of amino acids (monomers)
What is metabolism?
the complex series of chemical reactions that occur within the body to convert nutrients from food into energy
What are tight junctions? Plasmodesmata?
A tight junction is a watertight seal between two adjacent animal cells that prevents substances from leaking out between them.
Plasmodesmata are channels that directly connect plant cells, allowing for the exchange of materials between them
How do neighboring cells communicate in plants? Animals?
Plant cells communicate through specialized channels called “Plasmodesmata” which directly connects their cell membranes
Animal cells primarily use “gap junctions” to communicate with each other.
You are made of about 5000000000 individual cells. How is it that different cells in your body can have different shapes? How is it that when you stand up all your mitochondria in all your cells don’t fall to the bottom of the cells? How is it that all these cells don’t just fall down when you stand up, but stay together in the shape of you?
- Different cell shapes:
Different cells have different shapes because they are specialized to perform specific functions, like muscle cells, red blood cells, and nerve cells - Mitochondria don’t fall:
Mitochondria don’t fall to the bottom of your body because they are connected to a cytoskeleton network, made up of proteins like microtubules and actin filaments. - Our cells stay together and maintain their shape due to cell adhesion molecules (CAMs) and extracellular matrix (ECM)
