Cell Structure and Function Flashcards 2

23-57

What is the nucleus?

Contains most of the genes in a eukaryotic cell, averaging about 5 microns in diameter.

What is the nuclear envelope?

A double membrane enclosing the nucleus, about 20-40 nm apart, featuring nuclear pore complexes for macromolecule passage.

What is the nuclear lamina?

A network of intermediate filaments lining the nuclear side of the envelope, maintaining the nucleus's shape.

What is chromatin?

Fibrous material of DNA and associated proteins organized in the nucleus.

What are chromosomes?

Separate structures formed when chromatin fibers coil up as the cell prepares to divide.

What is the nucleolus?

A region in the nucleus where rRNA is synthesized and assembled with proteins to form ribosomal subunits.

What are ribosomes?

Particles made of proteins and ribosomal RNA (rRNA) that perform protein synthesis.

What are the sizes of ribosomes in prokaryotes and eukaryotes?

Prokaryotes: 70S; Eukaryotes: 80S.

What do free ribosomes in the cytosol synthesize?

Synthesize proteins that function within the cytosol.

What are bound ribosomes?

Attached to the outside of the endoplasmic reticulum or nuclear envelope, synthesizing membrane, organelle, or secretory proteins.

What is the endomembrane system?

The collection of membranes inside and around a eukaryotic cell, related through physical contact or vesicles.

What is the endoplasmic reticulum (ER)?

Network of membranous tubules and sacs called cisternae; continuous with the nuclear envelope.

What are the functions of the smooth ER?

Synthesis of lipids, glycogen metabolism, detoxification, calcium storage

What are the functions of the rough ER?

Synthesis of secretory, cell membrane, and organelle proteins, as well as phospholipids and ER-associated proteins.

What is the Golgi apparatus?

Major sites for carbohydrate synthesis; sorting and dispatching station for ER products; consists of flattened membranous sacs (cisternae).

What is the cis face of the Golgi apparatus?

Receiving side of the Golgi apparatus.

What is the trans face of the Golgi apparatus?

Shipping side of the Golgi apparatus.

What are the Golgi's protein and lipid alteration processes?

Transport vesicle from ER fuses to the cis face to transfer the material; proteins and lipids are altered; oligosaccharides are modified; polysaccharides are synthesized.

What are lysosomes?

Principal sites of intracellular digestion; contain hydrolytic enzymes requiring acidic pH to digest proteins, polysaccharides, fats, and nucleic acids.

What is autophagy?

Process by which cells recycle their own organic material, with organelles fused with a lysosome for digestion.

What are vacuoles?

Membrane-bound sacs with diverse functions, including food vacuoles, contractile vacuoles, and central vacuoles.

What are the roles of the mitochondria and the chloroplast?

Energy transformers of cells, with mitochondria performing cellular respiration and chloroplasts performing photosynthesis.

What is the structure of the mitochondria?

Enclosed by two membranes (inner and outer); the inner membrane is folded into cristae to increase surface area.

What does the matrix of the mitochondrion contain?

Contains ds circular DNA, prokaryote-like ribosomes (70S), enzymes in TCA cycle, and enzymes for β-oxidation of fatty acid.

What does the inner membrane of the mitochondrion contain?

Contains the electron transport chain and ATP synthase.

What is the chloroplast?

One of the generalized plant structures called plastids; found in mesophyll cells of leaves and in algae.

What kind of membranes does chloroplast have, and other components?

Inner and outer membranes; stroma containing ds circular DNA, 70S ribosomes, and enzymes for carbohydrate biosynthesis.

What do thylakoids contain?

Contain photosynthetic machinery, including light-absorbing pigments, electron carriers, and ATP-synthesizing apparatus.

What are microbodies?

Electron-dense cytoplasmic particles bound by a single membrane; contain oxidative enzymes; self-replicating like mitochondria.

What are peroxisomes?

Single membrane; contain enzymes transferring hydrogen to oxygen and producing H2O2, which is then converted to water.

What are glyoxysomes?

Specialized peroxisomes in fat-storing tissues of plant seeds; convert fatty acids to sugar for seedling energy.