Questions and Answers
What type of cell lacks membrane-bound organelles?
Which of the following are features of eukaryotic cells? (Select all that apply)
What is the function of the cell membrane?
It acts as a boundary between the cell and the external environment.
What does the nucleus contain?
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What is the primary function of chloroplasts?
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What structure is known as the powerhouse of the cell?
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What is water classified as due to its ability to dissolve many substances?
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What is the pH level of neutral solutions?
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What is homeostasis?
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What is the role of enzymes in biochemical reactions?
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What is the primary function of ribosomes?
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What is the primary function of the Golgi apparatus?
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The ______ is the structure within the nucleus that produces ribosomal RNA.
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What occurs during cellular respiration?
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What is the function of the sodium-potassium pump?
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Match the following terms with their descriptions:
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The ______ is a stack of thylakoids in chloroplasts.
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Study Notes
Prokaryotes vs. Eukaryotes
- Prokaryotes are single-celled organisms without a nucleus or membrane-bound organelles.
- Eukaryotes can be single-celled or multicellular and have a defined nucleus and membrane-bound organelles.
Cellular Structures
- The cell membrane serves as the barrier between the cell and its external environment.
- The cell wall is inflexible and found outside the cell membrane in plant cells, providing structure and support.
- The nucleus contains DNA and controls cellular activities.
- Chloroplasts are responsible for capturing solar energy for photosynthesis.
- The Golgi apparatus modifies, sorts, and ships proteins and lipids.
- Mitochondria are known as the powerhouse of the cell, generating ATP through aerobic respiration.
- Ribosomes are essential for synthesizing polypeptide chains and are present in all cell types.
Water Properties
- Water is the most abundant compound on Earth, existing in liquid, solid, and gaseous forms; it is a polar molecule with slight charges.
- Cohesion refers to water’s tendency to stick to itself, leading to high surface tension.
- Adhesion describes how water sticks to other substances.
- Capillary action is the ability of water to move against gravity due to its adhesive properties.
- High specific heat allows water to resist temperature changes, acting as a temperature buffer.
- Water is known as a universal solvent because it can dissolve various substances.
Acidity and pH
- Low pH indicates a more acidic solution, while high pH indicates less acidity.
- pH 7 is considered neutral, representing an average pH level.
Carbon and Molecules
- Carbon forms covalent bonds and can share four electrons, providing both strength and flexibility for various molecules.
- Carbohydrates are composed of simple sugars (saccharides) with a hydrogen to oxygen ratio of 2:1.
- Monosaccharides are the simplest form of carbohydrates, while oligosaccharides consist of short chains of sugar units. Polysaccharides are long chains.
Lipids and Proteins
- Lipids are insoluble in water, made up of fatty acids, and serve as energy storage.
- Proteins are complex polymers critical for muscle contraction, oxygen transport, and enzymatic activity.
- Nucleic acids store and transmit genetic information and are made up of nucleotides, which include a 5-carbon sugar, nitrogen base, and phosphate group.
Energy and Chemical Reactions
- Enzymes are proteins that act as catalysts, speeding up specific reactions without being consumed.
- Activation energy is the energy required to initiate a chemical reaction.
- ATP (adenosine triphosphate) stores and releases energy needed for cellular functions, while ADP (adenosine diphosphate) contains two phosphate groups.
- Phosphorylation involves transferring a terminal phosphate group to other compounds.
Cellular Processes
- Cellular respiration involves breaking down carbohydrates to produce ATP.
- Bioluminescence is light created by a chemical reaction that utilizes ATP.
- The Krebs cycle processes glycolysis products to yield molecules for the electron transport chain (ETC).
Membrane Properties
- Selective permeability allows certain materials to pass through the cell membrane while blocking others.
- Types of solutions affecting cells:
- Hypertonic: Higher solute concentration causes cell shrinkage.
- Hypotonic: Lower solute concentration causes cell swelling and is ideal for plant cells.
- Isotonic: Ideal for animal cells, allowing normal cell function.
Transport Mechanisms
- Diffusion is the movement of substances from high to low concentration.
- Osmosis specifically refers to the diffusion of water.
- Facilitated diffusion employs carrier molecules to transport substances across the membrane.
- Active transport involves energy use for processes like endocytosis, exocytosis, and the sodium-potassium pump.
Cytoplasm and Structural Components
- Cytoplasm is the gel-like substance containing dissolved materials and supporting cellular processes.
- The cytoskeleton provides internal structural support, composed of fine tubes and threads.
- Centrioles help organize microtubules during mitosis, found only in animal cells.
- The nucleolus produces ribosomal RNA within the nucleus.
- The nuclear membrane regulates material passage between the nucleus and cytoplasm.
Organelles and their Functions
- Vacuoles are membrane-bound areas that help maintain water balance within the cell.
- Smooth and rough endoplasmic reticulum (ER) differ in function; the smooth ER aids in lipid synthesis and protein processing, while the rough ER, with ribosomes, exports proteins.
- Lysosomes contain enzymes to break down toxic or unwanted substances.
- Plastids are varied membrane-bound structures with different functions, primarily in plant cells.
- Vesicles are storage or transport packages associated with endocytosis and exocytosis.
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Test your knowledge with these flashcards covering the essential concepts of biology in Module 1. Learn about key terms like prokaryotes, eukaryotes, and cellular structures such as the cell membrane and nucleus. Ideal for students preparing for the Keystone Biology exam.
