Lecture 1: Review of the cell

Question 1

The discovery of cells is generally credited to

Answer 1

Robert Hooke

Question 2

Antonie van Leeuwenhoek

Answer 2

First to examine a drop of pond water under the microscope and, to his amazement, observe the teeming microscopic “animalcules” that darted back and forth before his eyes. He was also the first to describe various forms of bacteria, which he obtained from two sources: water in which pepper had been soaked and scrapings from his teeth.

Question 3

Matthias Schleiden

Answer 3

Concluded that, despite differences in the structure of various tissues, plants were made of cells and the plant embryo arose from a single cell.

Question 4

Theodor Schwann

Answer 4

Schwann concluded that the cells of plants and animals are similar structures and proposed these two tenets of cell theory:
1. All organisms are composed of one or more cells.
2. The cell is the structural unit of life

Question 5

Schleiden and Schwann’s ideas on the origin of cells proved to be less insightful because

Answer 5

both agreed that cells could arise from noncellular materials

Question 6

Rudolf Virchow

Answer 6

Made a convincing case for the third tenet of cell theory:

3. Cells can arise only by division from a preexisting cell.

Question 7

Since the discovery of DNA as the genetic material, a fourth tenet of cell theory is sometimes added:

Answer 7

Cells contain genetic information in the form of DNA, and that information is passed from parent to daughter cell.

Question 8

Cells Are Highly Complex and Organized

Explain this with examples

Answer 8

• The more complex a structure, the greater the number of parts that must be in their proper place, the less tolerance for errors in the nature and interactions of the parts, and the more regulation or control that must be exerted to maintain the system. Cellular activities can be remarkably precise. DNA duplication, for example, occurs with an error rate of less than one mistake for every ten million nucleotides incorporated—and most of these are quickly corrected by an elaborate repair mechanism that recognizes the defect.
• Each type of cell has a consistent appearance when viewed under a high-powered electron microscope; that is, its organelles have a particular shape and location, from one individual of a species to another. Similarly, each type of organelle has a consistent composition of macromolecules, which are arranged in a predictable pattern.

Question 9

Just as individual organisms are generated by reproduction, so too are individual cells. Cells reproduce by division, a process in which ….. prior to…..(2):

Answer 9

• the contents of a mother cell are distributed into two daughter cells.
• Prior to division, the genetic material is faithfully duplicated, and each daughter cell receives a complete and equal share of genetic information

Question 10

Explain how the plant cell uses energy (generalized)

Answer 10

Virtually all of the energy utilized by life on the Earth’s surface arrives in the form of electromagnetic radiation from the sun. The energy of light is trapped by light absorbing pigments present in the membranes of photosynthetic cells. Light energy is converted by photosynthesis into chemical energy that is stored in energy-rich carbohydrates, such as sucrose or starch.

Question 11

For most animal cells, energy arrives prepackaged, often in the form of the sugar glucose. In humans, glucose is …..

Answer 11

released by the liver into the blood, where it circulates through the body delivering chemical energy to all the cells. Once in a cell, the glucose is disassembled in such a way that its energy content can be stored in a readily available form (usually as ATP) that is later put to use in running all of the cell’s myriad energy-requiring activities.

Question 12

. Virtually all chemical changes that take place in cells require

Answer 12

Enzymes

Question 13

Enzymes

Answer 13

molecules that greatly increase the rate at which a chemical reaction occurs

Question 14

metabolism

Answer 14

The sum total of the chemical reactions in a cell

Question 15

How does cells engage in mechanical activities?

Answer 15

Materials are transported from place to place, structures are assembled and then rapidly disassembled, and, in many cases, the entire cell moves itself from one site to another. These types of activities are based on dynamic, mechanical changes within cells, many of which are initiated by changes in the shape of motor proteins. Motor proteins are just one of many types of molecular “machines” employed by cells to carry out mechanical activities.

Cell itself and components in it are moving

Question 16

Explain how cell respond to stimuli

Covered+ react to+ evoke+ respond

Answer 16

Most cells are covered with receptors that interact with substances in the environment in highly specific ways. Cells possess receptors to hormones, growth factors, and extracellular materials, as well as to substances on the surfaces of other cells. Receptors provide pathways through which external stimuli can evoke specific responses in target cells. Cells may respond to specific stimuli by altering their metabolic activities, moving from one place to another, or even committing suicide.

Question 17

All living organisms have evolved from a single, common ancestral cell that lived more than three billion years ago:

Answer 17

LUCA

Question 18

Cells that are present in living organisms, share many features, including a … (3)

Answer 18

common genetic code, a plasma
membrane, and ribosomes.

Question 19

There were two basic classes of cells——distinguished by their — and the —–, or —, they contain

Answer 19

• prokaryotic and eukaryotic
• size
• types of internal structures
• membrane bound organelles

Question 20

Prokaryotic cells include

Answer 20

bacteria

Question 21

eukaryotic cells include (4)

Answer 21

protists, fungi, plants, and animals

Question 22

Eukaryotic cells almost certainly evolved from —- because —, —, —

Answer 22

• prokaryotic ancestors
• both types of cells share an identical genetic language, a common set of metabolic pathways, and many common structural features.

Question 23

nucleoid

Answer 23

The genetic material of a prokaryotic cell is present in a nucleoid: a poorly demarcated region of the cell that lacks a boundary membrane to separate it from the surrounding cytoplasm.

Question 24

nucleus

Answer 24

Eukaryotic cells possess a nucleus: a region bounded by a complex membranous structure called the nuclear envelope.

Question 25

chromatin

Answer 25

the chromosomal DNA of eukaryotes, that is tightly associated with proteins to form a complex nucleoprotein material

Question 26

Mitochondria

Answer 26

Where chemical energy is made available to fuel cellular activities

Question 27

Endoplasmic reticulum

Answer 27

Where many of a cell’s proteins and lipids are manufactured

Question 28

Golgi complexes

Answer 28

Where materials are sorted, modified, and transported to specific cellular destinations

Question 29

Eukaryotic cells also contain numerous structures lacking a surrounding membrane. Included in this group are (2)

Answer 29

1. the elongated tubules and filaments of the cytoskeleton
2. ribosomes

Question 30

What do the elongated tubules and filaments of the cytoskeleton do?

Answer 30

Participate in cell contractility, movement, and support

Question 31

What do ribosomes do? (2)

Answer 31

Function as “workbenches” on which the proteins of the cell are manufactured. These structures participate in the assembly of proteins by a similar mechanism in both types of cells.

Question 32

What is a flagellum and how does it work?

Answer 32

The movement of a prokaryotic cell may be accomplished
by a thin protein filament, called a flagellum, which protrudes from the cell and rotates. The rotations of the flagellum, which can exceed 1000 times per second, exert pressure against the surrounding fluid, propelling the cell through the medium.

Question 33

Prokaryotes are divided into two major taxonomic groups, or domains:

Answer 33

the Archaea (or archaebacteria) and the Bacteria (or eubacteria)

Question 34

Covalent bonds

What it is+ Why it forms, goberned by what principle?

Answer 34

Pairs of electrons are shared between pairs of atoms.
The formation of a covalent bond between two atoms is governed by the fundamental principle that an atom is most stable when its outermost electron shell is filled.

Question 35

The formation of a covalent bond is —-, which must be —– at some later time if then bond is to be broken

Answer 35

accompanied by the release of energy
reabsorbed

Question 36

Polarized

Answer 36

A molecule such that one of the atoms has a partial negative charge and the other a partial positive charge

Question 37

What are polar molecules + what they usually contain (2)

Answer 37

Molecules, such as water, that have an asymmetric distribution of charge (or dipole) are referred to as polar molecules.
Polar molecules of biological importance contain one or more electronegative atoms, usually O, N, and/or S.

Question 38

Nonpolar+ex (2)

Answer 38

Molecules that lack electronegative atoms and strongly polarized bonds, such as molecules that consist entirely of carbon and hydrogen atoms. (Symmetic distribution of charge)

Question 39

Noncovalent bonds

What do they depend and not depend on?

Answer 39

A relatively weak chemical bond based on attractice forces between atoms having an opposite charge.

Question 40

Tell me about the strength of ionic bonds in cells

Answer 40

The strength of ionic bonds in a cell is generally weak (about 3 kcal/mol) due to the presence of water, but deep within the core of a protein, from which water is often excluded, such bonds can be much stronger.

Question 41

Hydrogen bonds in biological molecules are easily —.

Answer 41

broken

Question 42

What happens in a hydrophobic effect?+ ex

Answer 42

In a hydrophobic effect, the nonpolar (hydrophobic)
molecules are forced into aggregates, which minimizes their exposure to the surrounding water molecules.
- basis for the formation of lipid bilayer membranes

Question 43

Each molecule of water can form hydrogen bonds with as many as —- other water molecules

Answer 43

four

Question 44

Water molecules form hydrogen bonds with organic molecules that contain polar groups, such as —- and —-, which ensure their —- within the cell.

Answer 44

• amino acids and sugars
• solubility

Question 45

organic

Answer 45

a chemical with a structure
based on carbon-carbon bonds

Question 46

biochemicals

Answer 46

The compounds produced by living organisms

Question 47

Functional groups

Answer 47

Particular groupings of atoms that often behave as a unit and give organic molecules their physical properties, chemical reactivity, and solubility in aqueous
solution

Question 48

macromolecules

What they are+do

Answer 48

Huge and highly organized molecules that form the structure and carry out the activities of cells. Because of their size and the intricate shapes that macromolecules can assume, some of these molecular giants can
perform complex tasks with great precision and efficiency.

Question 49

Macromolecules can be divided into four major categories:

Tell me about them

Answer 49

• proteins, nucleic acids, polysaccharides, and certain lipids.
• The first three types are polymers composed of a large number of low-molecular-weight building blocks, or monomers. These macromolecules are constructed from monomers by a process of polymerization.

Question 50

Metabolic pathway

Answer 50

In the cell, each series of chemical reactions is termed a
metabolic pathway.

Question 51

Polysaccharides, proteins, and nucleic acids consist of monomers (subunits) linked together by —–

Answer 51

covalent bonds