Chapter 3 Connect Questions

What chemical property of phospholipids is key to the formation of the cell membrane?

The hydrophilic head and hydrophobic tails

How does the chemical structure of phospholipids enable them to form a bilayer in water?

The hydrophilic heads make contact with water, whereas the hydrophobic tails avoid water. When many phospholipids join, the hydrophilic heads and hydrophobic tails align, forming a bilayer

Why are ions and polar molecules unable to pass directly through the cell membrane?

The interior of the phospholipid bilayer is hydrophobic

Which parts of the cell interact to produce and secrete a complex substance such as milk?

The nucleus, ribosomes (on rough ER), smooth ER, Golgi apparatus, vesicles, and cell membrane interact to secrete milk Mitochondria provide the energy needed for this process.

What three components of the cell theory were devised in the mid-1800's?

1) All cells originate from preexisting cells. 2) The cell is the fundamental unit of all life. 3) All organisms are made of one or more cells.

The organelle that is the site of photosynthesis in plant cells is the _____, which is a type of plastid.

Choloroplast

What is the function of the nucleus and its contents?

Contains DNA and the nucleolus. mRNA molecules are also produced here, and exit through nuclear pores before participating in protein production

A human nerve cell that has an abormal shape most likely has a defective _____.

Cycoskeleton

The two-layered nuclear envelope separates the nucleus of a cell from the _____

Cytoplasm

What pieces are present in bacterial cells?

Cytoplasm, enzymes, DNA, and ribosomes

Name the components present in bacterial cells.

Cytoplasm, ribosomes, enzymes, and DNA

_____ are flattened membrane sacs within a chloroplast where photosynthetic pigments, such as chlorophyll, are embedded.

Thylakoids

The microfilaments, intermediate filaments, and microtubules shown in the picture comprise the _____, chich is a network of proteins that provide a structural framework within the cell.

Cytoskeleton

The watery mixture of ions, enzymes, and RNA within the cytoplasm is called the _____

Cytosol

In a cell, _____ is the genetic information of the cell, and RNA plays a role in the production of _____.

DNA; proteins

What are the functions of lysosomes?

Dismantling worn out organelles, break down large food particles into smaller subunits, lyse captured bacteria

How do magnetosomes help bacteria save energy?

Earth's magnetic fields are basically vertical, while its O2 concentrations run horizontally. Because of this, bacteria know that by traveling along magnetic fields, they will eventually hit a section of optimal O2 levels.

Describe adaptations that increase the ration of surface area to volume in cells

Elongated or flattened cell shapes, an efficient transportation system, a water-filled vacuole, and improved efficiency help cells work around surface area limitations

The internal membranes of several organelles are interconnected and form the _____ system of eukaryotic cells.

Endomembrane

Peroxisomes are organelles that originate at the _____ and contain enzymes that dispose of toxic substances.

Endoplasmic reticulum

What is a network of sacs and tubules extending off the nuclear envelope and is where proteins and lipids are produced?

Endoplasmic reticulum

Oganelles called lysosomes contain _____ that break down food particles, old organelles, and other cellular debris.

Enzymes

What type of membrane protein speeds up chemical reactions?

Enzymes

What does a central vacuole in plants contain?

Enzymes, salts, pigments, sugars, and acids

Key genetic sequences suggest that archaea are more closely related to members of domain _____ than they are to members of Domain Bacteria.

Eukarya

What is the relationship between cells and organelles?

Eukaryotic cells contain specialized membrane-bounded organelles that carry out specific functions

If a eukaryotic cell is like a house, how is a prokaryotic cell like an efficiency (studio) apartment?

Eukaryotic: Features many different, specialized, internal compartments Prokaryotic: Smaller, and simpler in design, with fewer internal compartments. Despite this, it still carries out the exact same internal functions as the whole house

What are the differences between domains Bacteria and Archaea?

Evolutionary relationship to eukaryotes, chemical composition, and molecules that compose the cell membranes

What is the function of membrane proteins that are enzumes?

Facilitate chemical reactions

What are the function and definition of the "lysosomes"?

Function: Dismantles and recycles components of food, debris, captured bacteria, and worn-out organelles Definition: Sac containing digestive enzymes, and surrounded by a single membrane

What are the function and definition of the "Golgi apparatus"?

Function: Packages materials to be secreted; produces lysosomes Definition: Stack of flat membranous sacs

What are the function and definition of the "ribosome"?

Function: Primary location of protein synthesis Definition: Two globular subunits composed of RNA and protein

What type of cellular junction prevents stomach acid from leaking into the abdomen and digesting internal organs?

Tight junctions

What are the 3 types of junctions that link cells in animals?

Tight junctions, anchoring junctions, and gap junctions

What is the function of food vacuoles in amoebas?

To digest nutrients engulfed by the cell

What is the function of the contractile vacuole in Paramecium?

To pump excess water out of the cell

_____ proteins are embedded in the cell membrane and act as passageways for water-soluble materials into or out of the cell.

Transport

What are some functions of membrane proteins?

Transport proteins: Move substances in and out of cells Enzymes: Facilitate chemical reactions Recognition proteins: Allow the body to recognize its own cells Adhesion proteins: Allows cells to stick together Receptor proteins: Bind to molecules outside the cell and trigger chemical reactions inside the cell

What are the main components of phospholipid molecules, which are the main constituents of cell membranes?

Two fatty acids, glycerol molecule, and phosphate group

Why are cilia and flagella important?

Unicellular organisms may use either cilia or flagella to move toward food or other resources. IE: Sperm cells have flagella, and cilia sweep substances along the respiratory tract and the female reproductive tract.

Plant cells have large central ___ where water, salts, and sugars are stored and where materials are broken down and recycled with enzymes similar to lysosomes in animal cells.

Vacuoles

Turgor pressure in plant cells results from the expansion of the central vacuole as it fills with _____

Water

What are the function and definition of the "Chloroplast"?

Function: Produces food (sugars) by photosynthesis Definition: Two membranes enclosing stacks of membrane sacs, which contain photosynthesis pigments and enzymes. Contains DNA and ribosomes

What are the function and definition of the "Central vacuole"?

Function: Produces turgor pressure, recycles cell contents, and contains pigments Definition: Sac containing enzymes, acids, water-soluble pigments, and other solutes. Surrounding by a single membrane

What are the function and definition of the "cell wall"?

Function: Protects the cell, provides shape, and connects adjacent cells Definition: Porous barrier of cellulose and other substances in plants

What are the function and definition of the "Mitochondrion"?

Function: Releases energy from food by cellular respiration Definition: Two membranes, with the inner membrane folded into enzyme-studded cristae. Contains DNA and ribosomes

What are the function and definition of the "Endoplasmic reticulum"?

Function: Rough ER that produces proteins destined for secretion from the cell; smooth ET synthesizes lipids and detoxifies drugs and poisons Definition: Membrane network studded with ribosomes (rough ER) or lacking ribosomes (smooth ER)

What are the function and location of "tight junctions"?

Function: Seals the space between animal cells by fusing cell membranes Location: Cells in inner lining of stomach and small intestine

What are the function and definition of the "nucleus"?

Function: Separates DNA from the rest of the cell, is the site of the first step in protein synthesis, and the nucleolus produces ribosomal subunits Definition: Perforated sac containing DNA, proteins, and RNA; all surrounded by a double membrane

What are the function and location of "plasmodesmata"?

Function: To allow substances to move between plant cells Location: Plant cell walls

What are the function and location of "Anchoring (adhering) junctions"?

Function: To connect adjacent animal cell membranes in one spot; connect cells to the extracellular matrix Location: Cells in outer skin layer

What are the function and location of "gap junctions"?

Function: To form channels between animal cells, allowing exchange of substances Location: Muscle cells in the heart and digestive tract

What are the function and definition of the "cytoskeleton"?

Function: Transports organelles within the cell and maintains cell shape. The structural basis for flagelia/cilia, and connects adjacent cells Definition: A network of protein filaments and tubules

What are the function and definition of the "Peroxisome"?

Function: disposes of toxins, breaks down fatty acids, and eliminates hydrogen peroxide Definition: Sac containing enzymes, often forming visible protein crystals. Surrounded by a single membrane

Describe the functions and chemical composition of a plant cell wall

Functions: Gives shape, regulates cell volume, and prevents a cell from bursting if it takes in too much water. They also participate in the specialization of plant cells. Composition: Plant cell walls are made of mostly cellulose, and also contain hemicellulose, pectin, and many types of protein.

The _____ is a series of flattened sacs that sorts and packages materials into vesicles to be sent to the cell membrane.

Golgi apparatus

What are plasmodesmata? What type of animal cell junction are plasmodesmata most similar to?

Plasmodesmata are tunnels through the cell wall, which plant cells can use to communicate with their neighbors. They are most similar in function to gap junctions, which allow the exchange of substances between cells.

How do prokaryotic cells differ from eukaryotic cells?

Pro. cells lack a nucleus and other membrane-bounded organelles, have chemically unique cell walls, and are typically much smaller than eukaryotic cells.

_____ cells are the simplest forms of life and lack a nucleus.

Prokaryotic

What component of cell membranes functions in a diversity of roles, including recognition, transport, adhesion, and facilitating reactions?

Proteins

What are the main components of the cytoskeleton?

Proteins that assemble into microfilaments, intermediate filaments, and microtubules

What are some functions of the cytoskeleton?

Provides structural framework for the cell, acts as an internal transportation system, allows the cell to move, and connects cells to one another

Which components are present in both prokaryotic and eukaryotic cells?

RNA, DNA, ribosomes, and cytoplasm

Why might biologist avoid using the term extremophile prokaryotes to refer to Domain Archaea?

Reason #1: Many archaea are found in moderate environment. Reason #2: Bacteria (which are prokaryotes) are often found in extreme environments This delineates the two due to the fact that the environments they each inhabit are not accurately described by that name.

What cell structure binds to mRNA coming from the nucleus and manufactures proteins?

Ribosome

The nucleolus is a dense spot in the nucleus where components of _____ are assembled

Ribosomes

Proteins to be secreted outside of a eukaryotic cell are formed at ribosomes on the surface of the _____ endoplasmic reticulum.

Rough

The _____ produced in the nucleus enters the cytoplasm and binds to ribosomes, the sites of protein synthesis

mRNA

Which molecules and structures occur in all cells?

All cells have DNA, proteins, RNA, ribosomes, a watery cytoplasm, and a cell membrane

How did the researchers determine that both magnetism and oxygen guided bacteria movements?

An experiment in which bacteria in small glass tubes were free to select their optimal O2 concentration which researchers manipulated the magnetic field. The bacteria would turn to face the position of the magnetic field, but remain primarily where the concentration of oxygen was the optimal.

Compare and contrast barteria and archaea

Bacteria and archaea are small, single-celled organisms that lack nuclei and membrane-bounded organelles. The two groups differ in the composition of the cell wall, cell membrane, and flagella; they also differ in key DNA sequences.

Why are cells, not atoms, the basic units of life?

Cells are the first level of organization that displays all the characteristics of life, and only living things are composed of cells. Both living and non-living things have atoms and molecules across the board.

What plant cell organelle can occupy up to 90% of the cell volume and can exert turgor pressure agains the cell membrane when it acquires water?

Central vacuole

Describe how form fits function for three organelles

Golgi apparatus: A series of flat, membrane-enclosed sacs that acts as the processing center of the cell. Each sec moves a molecule closer to its final form, and has different enzymes to carry out the reactions. Lysosomes: Membrane-enclosed spheres that degrade and recycle materials in the cell. The membrane can pass materials, and encloses an enzyme solution used to break down organic materials. These enzymes work most efficiently at the acidic pH of the lysosome, rather than the neutral pH of the cytosol, so the organelle can degrade debris without harming the rest of the cell. Mitochondria: The powerhouse of the cell which converts energy from food into a form that the cell can use. Each mitochondrion has a highly folded inner membrane, which provides vast surface area for the reactions to occur within. The inner membrane also provides a separate compartment (the matrix) within the organelle where additional reactions can occur.

Lysosomes originate form vesicles that bud from the _____, and the enzymes contained in lysosomes are synthesized in the _____.

Golgie appartus; rough ER

What English physicist first observed the outlines of cells when he looked at cork from an oak tree?

Hooke

What are the components of the cytoplasm, outside the nuclear membrane?

Ions and enzymes, cytoskeleton, cytosol, and organelles

The _____ microscope is ideal for viewing living cells that are between 200 nanometers and 1 mm in size.

Light

What type of microscope passes light through a transparent or thinly sliced specimen to generate true-color views of cells?

Light microscope

What pieces are able to pass freely through the phospholipid bilayer?

Lipids, small nonpolar molecules, O2, and CO2

Rank the 3 main types of microscopes from lowest to highest potential magnification.

Lowest: Light microscope Mid: Scanning electron Highest: Transmission electron

What organelle of the endomembrane system breaks down debris, food, and old cell parts with special dismantling enzymes?

Lysosome

Which organelles are the cell's "recycling center"?

Lysosomes, vacuoles, and peroxisomes

All cells have a cell _____ that surrounds the cytoplasm and forms a boundary between the cell and its evironment.

Membrane

One property that is present in cells in domain Eukarya, but absent from those in domain Bacteria is _____.

Membranous organelles

Cytoskeletal components called _____ are long, thin rods of actin protein that are used in muscle contractions, stretching and compression, and anchoring of cells.

Microfilaments

How have microscopes advanced the study of cells?

Microscopes led to the discovery of cells, allow us to tell the type of cell (prokaryotic or eukaryotic), allow us to study the organelles, and basic functions of cells as they occur.

Which organelle houses the reactions that extract chemical energy from nutrient molecules?

Mitochondria

Cellular respiration extracts energy from food and takes place in the organelle called a _____.

Mitochondrion

Name all of the cell parts that are involved in the endomembrane system.

Nuclear envelope, Golgi apparatus, vacuoles, endoplasmic reticulum, lysosomes

What structures allow the passage of regulatory proteins into the nucleus and mRNA molecules out of the nucleus?

Nuclear pores

Inside the nucleus of a eukaryotic cell, the subunits of ribosomes are assembled in the _____

Nucleolus

In eukaryotic cells, the DNA that codes for the cell's proteins is stored in a membrane-bounded organelle called the _____

Nucleus

What are the original components of the cell theory, and what part of the theory came later?

Original two: Life is made of cells, and cells are the fundamental units of life. Third: Cells come from preexisting cells. Most recent: All cells have the same basic chemical composition, use energy, and contain DNA that is duplicated and passed on as each cell divides.

What organelle protects all eukaryotic cells from toxic substances or toxic by-products of chemical reactions?

Peroxisome

The cell membrane is composed of a type of lipid molecule called a(n) ___ which has two fatty acids and a phosphate group extending from a glycerol molecule.

Phospholipid

Where in the cell do phospholipid bilayers occur?

Phospholipid bilayers occur around organelles within the cell and form the plasma membrane

Within a single cell. which of the following is physically the smallest?

Phospholipid molecule

Chemically, how is a phospholipid different from a triglyceride?

Phospholipid: Two fatty acids and a phosphate group attached to a glycerol Triglyceride: Three fatty acids attached to a glycerol

What are the components of cell membranes?

Phospholipids, proteins, and steroids