Biology - A Human Perspective: Chapter 4 Flashcards

Question-and-answer flashcards covering key concepts from the notes (cells, endomembrane system, nucleus, organelles, cytoskeleton, ECM, and prokaryotic/eukaryotic distinction).

What is the main source of energy for the human body?

Glucose.

Which of the four molecules of life is made up of amino acids?

Proteins.

What kind of bond creates alpha helices and beta sheets in proteins?

Hydrogen bonds between the backbone of the polypeptide.

True or False: Uracil is found in both DNA and RNA.

False. Uracil is found in RNA; DNA contains thymine.

Which of the following are proteins: saturated fats, enzymes, trans fats, cellulose, fructose?

Enzymes.

Nucleic acids have a backbone made of what?

Sugar-phosphate backbone.

What are the basic units of life?

Cells.

Why must cells be small?

To exchange materials efficiently across the plasma membrane and maintain a favorable surface-to-volume ratio.

What is the plasma membrane primarily composed of?

A phospholipid bilayer with embedded proteins and carbohydrates.

How are the hydrophilic heads and hydrophobic tails oriented in the phospholipid bilayer?

Hydrophilic heads face outward toward water; hydrophobic tails face inward away from water.

What is the role of channel proteins?

They provide selective pathways for ions and hydrophilic molecules across the membrane.

What is the role of pumps in the plasma membrane?

Proteins that actively transport molecules using energy.

What is the nucleus?

The organelle that controls the cell’s activities and contains most of the cell’s DNA.

What is the nucleolus?

A structure where ribosomal RNA (rRNA) and ribosomal subunits are synthesized.

What are ribosomes and where can they be located?

Ribosomes synthesize proteins; they can be free in the cytoplasm or bound to the rough endoplasmic reticulum.

What is the endomembrane system?

A network of membranes within the cell that manufactures, processes, and transports proteins and lipids; includes the nuclear envelope, ER, Golgi apparatus, lysosomes, vesicles, and the plasma membrane.

What are the two kinds of endoplasmic reticulum and how do they differ?

Rough ER has ribosomes and makes proteins and membranes; Smooth ER lacks ribosomes and synthesizes lipids and detoxifies substances.

What is the function of the Golgi apparatus?

Modifies, sorts, and ships proteins; acts as a receiving and shipping dock and processes proteins.

What are lysosomes?

Digestive compartments with enzymes that break down waste, damaged organelles, and ingested particles.

What are vacuoles?

Membranous sacs with various functions such as food storage, central vacuoles in plants, pigment storage, and contractile vacuoles.

What energy process occurs in mitochondria?

Cellular respiration, producing ATP from chemical energy stored in food.

What are the two internal compartments of mitochondria?

Intermembrane space and the mitochondrial matrix.

What organelles perform photosynthesis in plants?

Chloroplasts.

What are the main components of a chloroplast?

Stroma, thylakoids, and granum; chloroplast DNA is also present.

What is the cytoskeleton and its three major fiber types?

A network of protein fibers providing support and movement; microfilaments (actin), intermediate filaments, and microtubules.

What are microfilaments used for?

Support the cell’s shape and form networks just inside the plasma membrane.

What are microtubules used for?

Shape the cell and serve as tracks for transport using motor proteins.

What structures move cells or move fluids over cells and what powers them?

Cilia and flagella; powered by motor proteins associated with microtubules.

What is the extracellular matrix (ECM)?

A network outside the plasma membrane composed of collagen; provides support and regulation and connects to the cytoskeleton via integrins.

What are integrins?

Attachment proteins that connect the ECM to the cytoskeleton.

What are the four common features of all cells?

Plasma membrane, cytosol, ribosomes, and DNA.

How do prokaryotic and eukaryotic cells differ?

Prokaryotes lack a membrane-enclosed nucleus and other organelles; eukaryotes have a nucleus and various organelles.

What is the nuclear envelope and its function?

A double membrane with pores that regulates movement into and out of the nucleus and is continuous with the ER.

What is chromatin?

DNA associated with proteins; diffuse form when not dividing and condenses into chromosomes during division.

What is the role of the nucleus in genetic control?

Contains the cell’s genetic instructions and directs protein synthesis.

What is the role of the endomembrane system’s vesicles?

They transport materials between organelles and to the plasma membrane.

What is the role of ribosomal subunits and where are they assembled?

Ribosomal subunits are assembled in the nucleolus and then exported to the cytoplasm to participate in protein synthesis.

Where are proteins synthesized by ribosomes on the ER transported to?

In vesicles to the plasma membrane or extracellular space (secretory proteins) or to membranes (membrane proteins).

What is the role of the rough vs. smooth ER in protein and lipid production?

Rough ER synthesizes proteins and adds membrane; smooth ER synthesizes lipids and detoxifies substances.

What is the central vacuole’s role in plant cells?

Hydrolytic functions, storage of substances, and maintaining turgor pressure.

What is the role of the mitochondrion’s matrix?

Contains mitochondrial DNA, ribosomes, and enzymes involved in cellular respiration.

What is the role of the stroma in chloroplasts?

Contains chloroplast DNA, ribosomes, and enzymes for the Calvin cycle.

What is the function of the extracellular matrix in animal cells?

Provides structural support, regulates cell behavior, and anchors cells to each other and to the cytoskeleton.