Unit 1 (week 1,2,3) Flashcards
1
Q
Cell membrane structure
A
- Phospholipid bilayer with hydrophobic tails and hydrophilic heads\n- Includes proteins, cholesterol, glycolipids, and glycoproteins\n- Provides a selectively permeable barrier between the cell and its environment
2
Q
Functions of the cell membrane
A
- Defines the cell and outlines its borders\n- Determines the nature of the cell’s interaction with its environment\n- Allows cells to selectively take in, exclude, and excrete substances
3
Q
Fluid mosaic model of the cell membrane
A
- Cell membrane is a fluid structure with proteins and lipids that can move laterally\n- Phospholipids form a bilayer with hydrophobic tails and hydrophilic heads\n- Proteins are embedded in or associated with the phospholipid bilayer
4
Q
Factors affecting membrane permeability and fluidity
A
- Increased temperature, unsaturated fatty acids, and decreased cholesterol increase permeability and fluidity\n- Decreased temperature, saturated fatty acids, and increased cholesterol decrease permeability and fluidity
5
Q
Roles of membrane proteins
A
- Transport proteins facilitate the movement of substances across the membrane\n- Receptor proteins bind to specific molecules and trigger cellular responses\n- Enzymatic proteins catalyze reactions on the cell surface\n- Structural proteins provide support and shape to the membrane
6
Q
Cholesterol’s role in the cell membrane
A
- Maintains membrane integrity and fluidity at extreme temperatures\n- Reduces membrane permeability at warmer temperatures\n- Prevents phospholipids from crystallizing at lower temperatures
7
Q
Glycolipids and glycoproteins in the cell membrane
A
- Face outward from the cell\n- Stabilize the lipid bilayer and contribute to membrane fluidity, flexibility, and integrity\n- Involved in cell-cell recognition and signaling, including immune system functions
8
Q
Passive vs. active transport across the cell membrane
A
- Passive transport requires no energy and moves substances down their concentration gradient\n- Active transport requires energy and moves substances against their concentration gradient
9
Q
Gradient
A
- Difference in concentration of a substance across a membrane\n- Solutes move from high to low concentration (down the gradient)\n- Solutes move from low to high concentration (against the gradient)
10
Q
Passive Transport
A
- Spontaneous movement of particles from high to low concentration\n- Does not require energy\n- Occurs via random kinetic movement\n- Net diffusion stops at equilibrium
11
Q
Osmosis
A
Movement of water across a semipermeable membrane from a region of low solute concentration to a region of high solute concentration
12
Q
Tonicity
A
- Measure of surrounding solution concentration relative to cell cytoplasm\n- Isotonic: same concentration as cytoplasm\n- Hypotonic: lower concentration than cytoplasm\n- Hypertonic: higher concentration than cytoplasm
13
Q
Facilitated Diffusion
A
- Allows diffusion of large, membrane-insoluble compounds down their concentration gradients\n- Uses membrane-spanning transport proteins\n- Does not require energy
14
Q
Ion Channels
A
- Pores that selectively allow ions to enter the cell\n- Ions flow down both concentration and electrochemical gradients
15
Q
Active Transport
A
- Movement across a membrane with an energy cost, often against concentration or electrochemical gradients\n- Requires specific integral membrane proteins and ATP
16
Q
Secondary Active Transport (Co-Transport)
A
- Uses the gradient created by active transport to power the movement of other molecules via facilitated diffusion\n- Typically involves two or more transport proteins
17
Q
Cell membrane function
A
- Selectively permeable to control movement of molecules in and out of the cell\n- Regulates cellular reaction sequences\n- Site for receptor molecules that enable cell signaling
18
Q
Passive transport
A
Allows molecules to move from high to low concentration without using energy
19
Q
Active transport
A
Requires energy to pump molecules against their concentration gradient
20
Q
Why are cells so small?
A
- Limits how small a cell can be\n- Allows for efficient exchange of materials across the cell membrane
21
Q
Characteristics of living organisms
A
- Acquire and use energy\n- Made up of membrane-bound cells\n- Process hereditary and environmental information\n- Capable of reproduction\n- Undergo evolution
22
Q
Features of bacterial cells
A
- Capsule for protection\n- Cell wall for structural support\n- Plasma membrane to separate from environment\n- Nucleoid region for DNA\n- Cytoplasm for metabolic enzymes and ribosomes
23
Q
Carbohydrates attached to lipids and proteins
A
Glycolipids and glycoproteins extend from the cell membrane’s outer surface
24
Q
Endoplasmic reticulum (ER)
A
- Highly folded network of membranes\n- Rough ER contains bound ribosomes for protein synthesis\n- Smooth ER has little to no bound ribosomes and is involved in lipid synthesis, cellular detoxification, and calcium ion storage
25
Golgi apparatus
Part of the endomembrane system that modifies, packages, and transports lipids and proteins
26
Lysosomes
The cell's recycling center, containing enzymes that break down waste and cellular components
27
Peroxisomes
Organelles that convert hydrogen peroxide (H2O2), a toxic byproduct of some reactions, into water and oxygen using the enzyme catalase
28
Mitochondria
- Organelles that produce ATP, the cell's energy currency\n- Have their own DNA and ribosomes, supporting the endosymbiotic theory of their origin
29
Cytoskeleton
Network of protein filaments that provide structure and support to the cell, and facilitate movement and transport within the cell
30
Characteristics of polymers
- Long chains of similar repeating subunits\n- Formed via condensation (dehydration) reactions\n- Broken apart via hydrolysis reactions\n- Examples: polysaccharides, proteins, nucleic acids
31
Carbohydrate storage in the body
- 350 grams (1,400 calories) of carbs stored as glycogen in muscles\n- 90 grams (360 calories) of carbs stored in the liver
32
Common polysaccharides
- Starch - storage in plants\n- Glycogen - storage in animals\n- Cellulose - in plant cell walls\n- Chitin - structural component in animals and fungi
33
Amino acid properties
- Some have polar side chains, others have nonpolar side chains\n- Can act as acids and bases by accepting and donating H+ ions
34
Acids
- Increase H+ concentration\n- Add H+ to a solution
35
Bases
- Decrease H+ concentration\n- Add OH- or remove H+ from a solution
36
pH
The negative base 10 log of the molar concentration of H+
37
Protein denaturation
Changes in environment (temperature, pH, chemical) that alter a protein's shape
38
Lipids
- Not polymers\n- Glycerol and fatty acids or steroids\n- Non-polar, used for energy storage, membranes, insulation
39
Phospholipids
- Amphipathic (polar head, non-polar tail)\n- Primary component of biological membranes
40
Energy storage in plants vs animals
- Plants store energy as sugars (starch)\n- Animals store energy as lipids (fats)
41
Polymers
- Long chains of repeating subunits\n- Examples: polysaccharides, proteins, nucleic acids\n- Formed by dehydration reactions, broken by hydrolysis
42
Properties of life
- Reproduce\n- Grow and develop\n- Metabolism\n- Homeostasis\n- Respond to stimuli\n- Evolve
43
The scientific method
1. Observation\n2. Question\n3. Hypothesis\n4. Experiment\n5. Conclusion
44
Importance of controls in experiments
Controls allow for comparison of data and effects, and help eliminate alternate explanations of experimental results
45
Characteristics of a good hypothesis
- Testable\n- Written in "If, then" format\n- Falsifiable
46
Elements
- Cannot be broken down by chemical means\n- Fundamental building blocks of all matter
47
Compounds
Substances made up of two or more elements chemically combined
48
Atoms
- All matter is composed of atoms\n- Atoms have a central nucleus surrounded by electrons\n- Nucleus is made up of protons and neutrons
49
Isotopes
- Variants of an element that differ in the number of neutrons\n- Number of protons is fixed, changes in neutrons do not change the element
50
Ions
- Variants of an element that differ in the number of electrons\n- Share the same atomic number and mass but differ in charge\n- Important for nerve impulses, muscle contractions, and water balance
51
Polar Covalent Bonds
- Unequal sharing of electrons in a covalent bond\n- Caused by differences in electronegativity between atoms
52
Ionic Bonds
- Form when atoms with a strong attraction for electrons "steal" electrons from atoms with a weak attraction\n- Result in a positively and negatively charged ion
53
Polar bonds (hydrogen bonds)
- Bond between a hydrogen in a polar molecule and an electronegative atom in another polar molecule\n- Allow polar compounds to be soluble (hydrophilic) in water
54
Properties of water
- Plentiful, covers 75% of Earth's surface\n- Makes up 70-90% of living things' body weight\n- Exists as liquid, gas (vapor), and solid (ice) under normal temperatures\n- Liquid water is more dense than solid water (ice floats)\n- Has high heat of vaporization, aids in thermoregulation\n- Acts as both an acid (donates protons) and a base (accepts protons)
55
Stability of atoms
- Atoms are more stable when their outer valence electron shells are full\n- Atoms fill their outer shells by donating/receiving (ionic) or sharing (covalent) electrons\n- These interactions generate chemical bonds that can be non-polar, polar, or ionic
