Chapter 04 - The Cell - An Overview

Flashcards covering basic cell features, types of cells, organelles, and specialized structures from lecture notes.

From what were the first observed cells?

Cork

Who is credited with first observing the cell nucleus?

Robert Brown

Which scientist proposed that cells arise only from preexisting cells by division?

Rudolf Virchow

What is the most commonly used unit for measuring cell size?

Micrometer (μm)

How many millimeters is a human egg approximately 100 µm in diameter?

0.10 mm

What type of microscopy passes light directly through a stained and killed specimen?

Bright field microscopy

What type of microscopy uses lasers and a computer to produce sharp 3D images from fluorescently-stained specimens?

Confocal laser scanning microscopy

What type of microscopy uses a beam of electrons to scan a specimen and create a three-dimensional image?

Scanning electron microscopy

Why is there an upper limit to the surface area-to-volume ratio in a cell?

The surface area must be sufficient for adequate nutrient and waste exchange to sustain the cell's chemical activities.

Why can eggs be larger than other cell types?

Eggs contain a large store of nutrients.

Where is the cell's hereditary information stored?

DNA

What regulates the movement of molecules in and out of the cell?

Plasma membrane

What is the prokaryotic chromosome comprised of?

A highly folded mass of a single, circular molecule of DNA

What is the slime layer external to the prokaryotic cell wall called?

Glycocalyx

Where does photosynthesis occur in prokaryotes?

Plasma membrane

What is a function of prokaryotic common pili?

Biofilm formation

What is the function of sex pili in prokaryotes?

Transfer of DNA

How is E. coli propelled?

Rotating bundles of flagella

In cell fractionation, which cellular structure is isolated in a pellet after the first centrifugation?

Nuclei

Which cellular structure cannot be isolated during cell fractionation because it is destroyed when intact cells are lysed?

Plasma membrane

What does chromatin consist of?

DNA and associated proteins

What network of protein filaments lines and reinforces the inner surface of the nuclear envelope in animal cells?

Lamins

What is a eukaryotic chromosome composed of?

DNA and protein

What is the semiliquid substance within the nucleus called?

Nucleoplasm

What is synthesized in the nucleoli, found within the nucleus?

Ribosomal subunits

How did researchers identify the nuclear localization sequence?

By infecting cells in culture with viruses with sequential amino acid deletions in a known nuclear protein, then microscopically determining cellular localization.

What organelles will be numerous in cells actively making large quantities of proteins?

Ribosomes

Which organelle is involved in the synthesis of lipids?

Smooth endoplasmic reticulum

Cells actively secreting enzymes would likely carry out more of which process?

Exocytosis

Where are the enzymes that destroy the webbing between fingers during human development probably localized?

Lysosomes

At what pH do lysosomal enzymes function best?

About 5

Which organelle contains hydrolytic enzymes for the digestion of proteins, lipids, nucleic acids, and polysaccharides?

Lysosome

Trace the correct path in the endomembrane system for a protein, starting with its synthesis in the rough ER.

Rough ER → Golgi complex → vesicle → plasma membrane

How did researchers identify proteins involved in the secretory pathway?

By interfering with protein translation and examining the cell's ability to transport fluorescently tagged proteins.

Where does aerobic cellular respiration occur?

Mitochondria

What are converted to water and carbon dioxide during ATP synthesis in cellular respiration?

O2 and glucose

What greatly increases the surface area of the inner mitochondrial membrane?

Cristae

Why do scientists believe mitochondria may have evolved from ancient bacteria?

Both have their own DNA and ribosomes.

Which organelles contain enzymes for reactions linking major biochemical pathways, including fat, amino acid, and alcohol breakdown?

Microbodies

In which small, specialized membrane-bound organelles does the breakdown of toxic hydrogen peroxide occur?

Peroxisomes

From what are cytoskeletal elements assembled?

Proteins

From what are microfilaments assembled?

Actin

From what are microtubules assembled?

Tubulin

In animal cells, what elements radiate from the cell center to anchor organelles and provide tracks for vesicle movement?

Microtubules

What extends from the base to the tip of a eukaryotic flagellum or cilium?

A bundle of microtubules

From which cellular components do eukaryotic cilia and flagella arise?

Centrioles

How do flagella bend?

Dynein motor proteins slide microtubule doublets over each other

Which organelle shares many similarities with the chloroplast?

Mitochondrion

Of what process are chloroplasts the site?

Photosynthesis

What do chloroplasts utilize light energy to make?

Carbohydrates

Where is starch stored in plant cells?

Amyloplasts

In which organelle are grana and thylakoids found?

Chloroplasts

In a mature plant cell, what may occupy more than 90% of the cell's volume?

The central vacuole

What is the membrane surrounding the central vacuole called?

Tonoplast

How do plant cells grow primarily?

By increasing the pressure and volume of the central vacuole

In which types of cells are cell walls found?

Plant and fungal cells

In plant cells, what provides cellular support and protects the cell from pathogens?

Cell wall

From what is the plant cell wall primarily composed?

Highly branched carbohydrates (cellulose)

What holds the walls of adjacent plant cells together?

Middle lamella

What more rigid structure is added to the cell wall as a plant cell grows and matures?

Secondary cell wall

How do plant cells permit ions and small molecules to move between adjacent cells?

Through cytoplasmic channels called plasmodesmata

Loss of cell adhesion molecules in cancerous cells is best associated with what trait?

Migration to new locations in the body

In normal cells, what is partially responsible for the cell's ability to recognize other cells as 'self'?

Cell adhesion molecules

What type of junction are desmosomes?

Anchoring junction

What is the function of tight junctions?

Seal the spaces between cells

What is the function of gap junctions?

Allow ions and small molecules to pass between cells

What allows for communication between heart muscle cells, contributing to coordinated beating?

Gap junctions

What are the main components of the extracellular matrix?

Glycoproteins

With whom do systems cell biologists often work to develop models of cellular processes?

Mathematicians and computer scientists

Which molecules communicate changes from the extracellular matrix to the cytoskeleton, integrating external and internal cellular changes?

Fibronectin and integrin

Which cell type(s) have ribosomes?

All living cells

Which cell type(s) have a cell membrane?

All living cells

Which cell type(s) have a nucleoid?

Prokaryotic cells only

Which cell type(s) have mitochondria?

Eukaryotic cells only

What is the cellular structure labeled 'E' in a eukaryotic plant cell?

Chloroplast

What is the cellular structure labeled 'H' in a eukaryotic plant cell?

Plasma membrane

What is the cellular structure labeled 'B' in a eukaryotic plant cell?

Golgi complex

What is the cellular structure labeled 'I' in a eukaryotic plant cell?

Smooth ER

What is the cellular structure labeled 'M' in a eukaryotic plant cell?

Nucleus

What is the cellular structure labeled 'J' in a eukaryotic plant cell?

Free ribosomes

What is the cellular structure labeled 'A' in a eukaryotic plant cell?

Mitochondrion

What is the cellular structure labeled 'G' in a eukaryotic plant cell?

Cell wall

What is the cellular structure labeled 'D' in a eukaryotic plant cell?

Central vacuole

What are the cellular structures labeled 'F' in a eukaryotic plant cell?

Microtubules

What is the cellular structure labeled 'C' in a eukaryotic plant cell?

Vesicle

Why are viruses not considered living organisms?

They consist only of a nucleic acid molecule surrounded by a protein coat and cannot carry out all activities of life like reproduction, response to stimuli, or growth.

How are animal and plant cells similar and different?

Both have a plasma membrane, nucleus, mitochondria, ER, ribosomes, and Golgi complex. Plant cells also have a cell wall, central vacuole, and chloroplasts, which animal cells lack.

What evolutionary advantage do prokaryotes have over eukaryotes?

Prokaryotes are biochemically more versatile, using various substances for energy, synthesizing organic molecules from inorganic materials, and living in almost all regions of Earth.

Where is cellular energy produced in prokaryotic cells, since they lack mitochondria?

The cell membrane contains most of the molecular systems needed to metabolize food molecules to generate ATP.

How would the internal structure of a pancreatic cell differ from a muscle cell?

Both have the same organelles, but in different proportions. Pancreatic cells (secreting hormones/enzymes) would have extensive rough ER, while muscle cells (contraction) would have many mitochondria for energy.

As the total surface area of a cell increases, does the surface area/volume ratio decrease?

True

Do all cells have DNA for genetic information, a plasma membrane, and mitochondria for energy generation?

False, only eukaryotic cells have mitochondria for energy generation.

Do some prokaryotes have a capsule, an external polysaccharide layer protecting them from physical damage?

True

Do proteins on the cell surface label cells as 'self' for immune system identification?

True

Does lipid synthesis occur in the Golgi complex?

False, lipid synthesis occurs in the smooth ER. The Golgi complex is involved in protein modification.

Do mitochondria convert solar energy into chemical energy?

False, chloroplasts convert solar energy into chemical energy. Mitochondria generate ATP from glucose and oxygen.

Are amyloplasts responsible for the colors of ripening fruits or autumn leaves?

False, chromoplasts are responsible for the colors of ripening fruits or autumn leaves. Amyloplasts store starch.

Do tonoplasts store salts, organic acids, sugars, storage proteins, and pigments in plant cells?

False, tonoplasts are the membrane surrounding the central vacuoles, which store these substances.

Are gap junctions connecting nerve cells in dental pulp responsible for discomfort when teeth are damaged?

True

Are the primary functions of the extracellular matrix protection and support?

True