Cell Structure and Function: Organelles, Membranes, and Energy in Biology

What are the basic structural and functional units of every organism?

Cells

What are the two main types of cells?

Prokaryotes and eukaryotes

What is a defining feature of prokaryotic cells?

They lack internal membrane-bound organelles.

Where is DNA located in prokaryotic cells?

In the nucleoid region

What is a defining feature of eukaryotic cells?

They contain membrane-bound organelles.

Where is DNA located in eukaryotic cells?

In the nucleus

What are organelles?

Membrane-bound structures in eukaryotic cells.

Name two classifications of organelles.

Endomembrane system and energy organelles.

What is the function of mitochondria?

Convert energy to forms that cells can use for work.

What is the role of chloroplasts?

Convert light energy into chemical energy through photosynthesis.

What is compartmentalization in eukaryotic cells?

The presence of membrane-bound organelles allows different metabolic processes to occur in separate locations.

What is the nuclear envelope?

A double membrane surrounding the nucleus that regulates entry and exit of materials.

What is the nucleolus?

A dense region in the nucleus where ribosomal RNA (rRNA) is synthesized.

What is the process of DNA being transcribed into mRNA called?

Transcription

What is the process of mRNA being translated into proteins called?

Translation

What must happen to mRNA before it leaves the nucleus?

It must be modified.

What do ribosomes do?

They decode information in mRNA and form chains of amino acids to create proteins.

What is the endomembrane system?

A system of organelles and subcellular components that interact to modify, package, and transport materials in the cell.

What are lysosomes?

Organelles that contain digestive enzymes to break down waste materials.

What is the function of the central vacuole in plant cells?

To store nutrients and waste products, and help maintain turgor pressure.

What is the function of plasmodesmata in plant cells?

They allow for communication and transport of materials between plant cells.

What are ribosomes made of?

Ribosomal RNA and protein

What is the primary function of ribosomes?

To synthesize proteins

Where are free ribosomes located?

In the cytosol

What type of proteins do free ribosomes produce?

Proteins that function only within the cytosol, such as enzymes

What are bound ribosomes attached to?

The endoplasmic reticulum or nuclear envelope

What is the function of the endoplasmic reticulum?

Provides mechanical support and intracellular transport

What are the two types of endoplasmic reticulum?

Rough ER and Smooth ER

What distinguishes rough ER from smooth ER?

Rough ER has ribosomes bound to its membrane, while smooth ER does not

What is the primary function of smooth ER?

To synthesize lipids and detoxify the cell

What are the flattened membranous sacs in the Golgi complex called?

Cisternae

What is the role of the cis face of the Golgi complex?

Receives vesicles from the endoplasmic reticulum

What happens at the trans face of the Golgi complex?

Sends vesicles back out into the cytosol or to the plasma membrane for secretion

What functions does the Golgi complex perform?

Receives, modifies, sorts materials, adds molecular tags, and packages materials into transport vesicles

What is one function of lysosomes?

To hydrolyze (digest) macromolecules

What is autophagy in relation to lysosomes?

The recycling of the cell's own organic materials and dysfunctional organelles

What are peroxisomes?

Membrane-bound metabolic compartments that are not part of the endomembrane system

What reaction do peroxisomes catalyze?

Reactions that produce hydrogen peroxide (H2O2)

What is the function of catalase in peroxisomes?

To break down hydrogen peroxide into water and oxygen

What are vacuoles?

Vesicles that stem from the ER and Golgi, involved in selective transport

How do animal cell vacuoles differ from plant cell vacuoles?

Animal cells have smaller vacuoles, while plant cells have a large central vacuole

What is the role of the central vacuole in plant cells?

Stores nutrients and water, important for turgor pressure

What is the primary function of mitochondria?

Site of cellular respiration

What are the two compartments created by the inner membrane of mitochondria?

Intermembrane space and mitochondrial matrix

What is contained in the mitochondrial matrix?

Enzymes for cellular respiration, ATP, mitochondrial DNA, and ribosomes

How does the number of mitochondria relate to a cell's metabolic activity?

Cells with high metabolic activity have more mitochondria

What organelle is responsible for photosynthesis in plants?

Chloroplast

What pigment is found in chloroplasts that is essential for photosynthesis?

Chlorophyll

What are thylakoids in chloroplasts?

Membranous sacs that can organize into stacks called grana

What is the stroma in chloroplasts?

The fluid around thylakoids where the Calvin cycle occurs

What does the Endosymbiont Theory propose?

Mitochondria and chloroplasts evolved from free-living prokaryotic cells via endosymbiosis

What are some pieces of evidence supporting the Endosymbiont Theory?

Double membrane, ribosomes, circular DNA, and ability to function independently

What is the cytoskeleton?

A network of fibers throughout the cytoplasm providing structural and mechanical support

What are the three types of fibers in the cytoskeleton?

Microtubules, microfilaments, and intermediate filaments

What is the function of microtubules?

Serve as structural support and assist in chromosome movement during cell division

What are microfilaments made of?

Thin solid rods made of the protein actin

What role do microfilaments play in muscle contraction?

They work with myosin to cause contraction

What are intermediate filaments?

Fibrous proteins that maintain cell shape and anchor organelles

In a liver tissue experiment, which organelle is responsible for detoxifying alcohol?

Mitochondria

In the liver tissue experiment, which organelle removes damaged parts of organelles?

Lysosomes

What steps do lysosomes take to remove damaged organelle parts?

They fuse with damaged organelles and use enzymes to break down and recycle components.