3A1 Structure and Function of Cells and Organelles Flashcards
Explain how cell structure and function vary across prokaryotic and eukaryotic organisms, with membranes, organelles, and levels of organization supporting diverse roles in sustaining life.
Define:
Cell
The basic structural and functional unit of all living organisms.
Cells are the smallest unit of life capable of performing all life processes, such as growth, metabolism, and reproduction.
Define:
organelles
A subcellular structure that completes a specific job within a cell.
They can be membrane-bound (surrounded by a lipid bilayer) or non-membrane bounded. The structure and function of these units varies depending on the type of cell.
Define:
eukaryotic cell
A cell with a defined nucleus.
Organisms with eukaryotic cells are referred to as eukaryotes. These include all animals, plants, fungi, seaweeds, and other organisms.
Define:
prokaryotic cell
A cell without a nucelus or membrane-bound organelles.
Organisms with these cells are called prokaryotes. This includes bacteria and archea. These cells are often smaller and more simple.
What is the cell membrane?
A selectively permeable barrier that surrounds the cell.
Present in both eukaryotes and prokaryotes, it controls the movement of substances in and out of the cell to maintain homeostasis.
What is the primary structure of the cell membrane?
The phospholipid bilayer.
The phospholipid bilayer forms the membrane’s basic structure, with hydrophobic tails facing inward and hydrophilic heads facing outward, creating a semi-permeable barrier.
What does selectively permeable mean for a cell membrane?
It allows some substances to pass through while blocking others.
This ensures essential nutrients enter, waste exits, and harmful substances are kept out.
True or False:
The phospholipid bilayer is rigid and immobile.
False
The membrane is fluid, allowing components like proteins and lipids to move within the bilayer.
Fill in the blank:
The cell membrane is often described as a _______ mosaic.
fluid
Just like a mosaic, the cell membrane is composed of many molecules. This model represents the dynamic and flexible nature of the membrane.
What are the functions of membrane proteins?
- Transport
- Signaling
- Structural Support.
Protein act as carriers, receptors for signals, and anchors for the cytoskeleton.
What role does cholesterol play in the cell membrane?
It maintains membrane fluidity and stability.
Cholesterol prevents the membrane from becoming too stiff in cold temperatures or too fluid in warm temperatures.
What is passive transport?
The movement of molecules across the membrane without energy (ATP) input.
It includes diffusion, osmosis, and facilitated diffusion, driven by concentration gradients.
True or False:
Active transport requires energy in the form of ATP.
True
Molecules against their concentration gradient, requiring ATP as energy.
Fill in the blank:
The movement of large molecules into the cell using vesicles is called _______.
endocytosis
It is a form of active transport that brings substances like nutrients or hormones into the cell.
What is the function of glycoproteins in the cell membrane?
Cell recognition and signaling.
They have carbohydrate chains that help cells identify and communicate with each other.
What organelles break down fatty acids and detoxify harmful substances?
Peroxisomes
They contain enzymes that metabolize fatty acids and detoxify harmful substances, producing hydrogen peroxide as a byproduct.
True or False:
Endocytosis and exocytosis are types of passive transport.
False
These processes involve vesicles and require energy, making them forms of active transport.
What is the function of the nucleus in a eukaryotic cell?
It houses the cell’s DNA and controls cellular activities.
The nucleus regulates gene expression, cell growth, and reproduction by controlling the synthesis of proteins and RNA.
What organelle is responsible for energy production in eukaryotic cells?
Mitochondrion
Mitochondria produce ATP through cellular respiration, providing energy for the cell’s functions.
What is the role of the endoplasmic reticulum (ER)?
It synthesizes proteins and lipids.
The Endoplasmic Reticulum has two main parts, the rough and smooth sections. The rough ER is studded with ribosomes for protein synthesis, while the smooth ER is involved in lipid production and detoxification.
What organelle is involved in the production of proteins?
Ribosomes
They are the sites of protein synthesis, translating mRNA into amino acid chains.
Fill in the blank:
The chloroplast is responsible for __________ in plant cells.
photosynthesis
Chloroplasts capture sunlight and convert it into chemical energy through photosynthesis, producing glucose and oxygen.
True or False:
The vacuole in plant cells stores water, nutrients, and waste products.
True
Vacuoles are large organelles in plant cells that maintain turgor pressure, store nutrients, and play a role in waste management.
What organelle assembles rRNA and combines it with proteins to form ribosomes?
Nucleolus
Found in the center of the nucelus, it is the site where ribosomal RNA (rRNA) is produced and combined with proteins to form ribosomes, which are crucial for protein synthesis.
True or False:
Cilia and flagella are involved in cell movement.
True
Cilia are short and numerous, moving fluid over the cell’s surface, while flagella are long and whip-like, helping the cell move through its environment.
What is the function of the cell wall in prokaryotic cells?
It provides structure and protection.
The cell wall maintains the shape of the prokaryotic cell and protects it from environmental stress.
True or False:
Prokaryotic cells have membrane-bound organelles.
False
Prokaryotic cells lack membrane-bound organelles, unlike eukaryotic cells that have structures like the nucleus and mitochondria.
Fill in the blank:
The __________ helps prokaryotic cells move in their environment.
flagella
They are long, whip-like structures that aid in motility.
What carries additional genetic information in prokaryotic cells?
Plasmid
They are small, circular DNA molecules that can carry genes, such as those for antibiotic resistance.
True or False:
Prokaryotic cells contain a true nucleus.
False
Prokaryotic cells do not have a true nucleus; their genetic material is not enclosed in a membrane-bound compartment.
Fill in the blank:
Prokaryotic cells go through ________ _______ for cell division.
binary fission
It is the method of asexual reproduction in prokaryotic cells, where the cell divides into two identical daughter cells.
What are the four levels of organization within a living organism?
- Cell
- Tissue
- Organs
- Organ System
The organ system is the highest level of organization, and is made up of multiple organs, which are made up of tissues, which is made up of cells.
What is the role of organs in multicellular organisms?
Each one has a specific function related to life.
They are made up of different types of tissues working together to carry out vital functions, such as the heart and the lungs.
What is a group of similar cells performing a specific function called?
Tissue
Tissues consist of similar cells working together to carry out a particular task, such as muscle tissue or nervous tissue.
What comes after tissues in the hierarchy of biological organization?
Organs
Tissues form organs, and organs work together within organ systems to perform complex functions.
Fill in the blank:
Groups of organs working together to perform a major function form a/an _______ ________.
organ system
Organ systems, like the digestive or respiratory system, consist of multiple organs that collaborate to carry out specific biological functions.
What is the function of the respiratory system?
To exchange gases, such as oxygen and carbon dioxide.
It includes organs like the lungs, which facilitate the exchange of gases necessary for cellular respiration.
What system controls and coordinates body activities?
Nervous system
It consists of the brain, spinal cord, and nerves, working together to transmit signals and regulate bodily functions.
What is the function of muscle tissue in the body?
To enable movement.
Muscle tissue contracts and relaxes to move the body and its parts, as seen in skeletal muscles, heart muscles, and smooth muscles.
What is the unique feature of muscle cells that enables movement?
They contain contractile proteins, such as actin and myosin.
Muscle cells, or myocytes, have specialized proteins that allow them to contract and enable movement in the body.
What is the largest organ in the human body?
Skin
It protects the body, regulates temperature, and allows sensory perception, making it the largest organ in terms of surface area.
True or False:
The digestive system is made up of only the stomach and intestines.
False
It includes various organs, such as the mouth, esophagus, stomach, and intestines, which work together to digest food.
What is the main function of red blood cells?
To transport oxygen throughout the bloodstream.
Also called erythrocytes, they are specialized for carrying oxygen from the lungs to tissues and carbon dioxide from tissues back to the lungs.
Fill in the blank:
Nerve cells, also known as ________, transmit electrical signals throughout the body.
neurons
These cells allow for communication within the nervous system.
What is the function of epithelial cells?
To form protective layers and secrete substances.
These cells line body surfaces and cavities, forming barriers and contributing to secretion and absorption in various organs.
True or False:
Epithelial cells are always a single layer thick.
False
They can be one layer thick (simple epithelium) or multiple layers thick (stratified epithelium), depending on the function and location.
Fill in the blank:
Muscle cells are characterized by the presence of __________, which allow them to contract.
myofibrils
Myofibrils contain actin and myosin filaments that slide past each other to generate contraction.
What cells are involved in the immune response?
White blood cells
(leukocytes)
They help fight infections by attacking foreign pathogens and producing antibodies.
Fill in the blank:
________ cells in the body help with gas exchange in the lungs.
Alveolar
These cells in the lungs facilitate gas exchange by allowing oxygen to pass into the blood and carbon dioxide to exit.
What is unique about the structure of red blood cells?
The biconcave shape allows the cell to carry more oxygen.
The shape increases the cell’s surface area, allowing it to efficiently carry and release oxygen.
How does a nerve cell transmit signals to other nerve cells?
Communication through axons and dendrites.
Axons transmit electrical impulses away from the cell body, while dendrites receive signals from other neurons, enabling communication across the nervous system.
What is the main difference between prokaryotic and eukaryotic cells?
Prokaryotic cells lack a nucleus, whereas eukaryotic cells have one.
Prokaryotes are simpler organisms like bacteria, while eukaryotes include plants, animals, fungi, and protists.
True or False:
All prokaryotes are unicellular.
True
Unicellular organisms, like bacteria and archaea, have no membrane-bound nucleus.
What are the two main groups of prokaryotes?
- Eubacteria
- Archaea
Eubacteria are typical bacteria, while Archaea are extremophiles, capable of living in harsh environments.
What type of cell contains chloroplasts?
Plant
These organelles responsible for photosynthesis, converting sunlight into chemical energy.
True or False:
Archaea can live in extreme environments like hot springs and salt lakes.
True
They are known as extremophiles, thriving in environments with extreme heat, salinity, or acidity.
What kind of organisms are protists?
Eukaryotic microorganisms.
They often unicellular, but some can be multicellular, and they can be autotrophic or heterotrophic.
What is the role of mitochondria in eukaryotic cells?
They generate energy in the form of ATP.
Mitochondria are known as the powerhouses of the cell, converting nutrients into energy that the cell can use.
What are the three kinds of multicellular eukaryotes?
- Plants
- Animals
- Fungi
Protists are considered eukaryotes, but they are generally unicellular.
True or False:
All eukaryotic cells have a cell wall.
False
Only plant cells, fungi, and some protists have a cell wall. Animal cells lack a cell wall.
Which group of organisms do fungi belong to?
Eukaryotes
Fungi are a distinct group of eukaryotic organisms that include molds, yeasts, and mushrooms.
Which eukaryotic kingdom does yeast belong to?
Fungi
They are unicellular fungi that play crucial roles in fermentation and can be found in various environments.
Fill in the blank:
Fungi reproduce both sexually and ________.
Asexually
Fungi can reproduce through spores, which can be produced either sexually or asexually, depending on the species.
