1. Journal Activity
Chapter 2 – What abnormality at the cellular or molecular level lies behind each of the following disorders? (a) cystic fibrosis (b) neurofibromatosis and (c) syndactyly.

2. Introducing Cells
Cellular activities and abnormalities underlie our inherited traits, quirks, and illnesses
Understanding genetic diseases can suggest ways to treat the condition
Figure 2.1
Lack of
dystrophin
An early sign of DMD is overdeveloped calf muscles that are a result in the inability to rise from a sitting position in the usual way. Lack of dystrophin causes skeletal muscle cells to collapse when they contract.

3. Introducing Cells Our bodies include more than 260 cell types
Somatic (body) cells have two copies of the genome and are said to be diploid
Gametes, sperm and egg cells have one copy of the genome and are haploid
Stem cells, which are diploid, can both replicate themselves and differentiate themselves for repair and replacement of specialized cells 3

7. Types of Cells Prokaryotic cells - Lack a nucleus Eukaryotic cells
Must maintain basic functions for growth and reproduction, responding to environment, and utilizing energy.
All cells can be divided into two main types
Prokaryotic cells
- Lack a nucleus
Eukaryotic cells
- Possess a nucleus and other organelles
Figure 2.2 7

8. Domains of Life
Biologists recognize three broad categories of organisms based on cellular complexity
Archaea – extreme bacteria
Eubacteria – more common forms of bacteria
Eukarya – Includes both unicellular and multicellular eukaryotes; higher cells 8

9. The Archaea and Eubacteria are similar in that they are single-celled organisms, but they differ in certain features of their RNA and membranes. These cells lack nuclei and other organelles and therefore are categorized as prokaryotes.
Eukaryotic cells are complex, with abundant and diverse organelles that compartmentalize biochemical reactions. Human cells are therefore eukaryotic.

10. Chemical Constituents
Cells contain four types of macromolecules
Type
Examples
Functions
Carbohydrates
Sugars, starches
Energy, structure
Lipids
Fats, oils
Membranes, hormones
Proteins
Myosin, collagen
Enzymes, structure
Nucleic Acids
DNA, RNA
Genetic information 10

11. Enzymes are proteins that catalyze the multitude of biochemical reactions that occur in the cell.
The study of nucleic acids is key to the field of genetics.

12. An Animal Cell Surrounded by the plasma membrane Contains: - Cytoplasm
- Organelles
- Divide labor by partitioning certain areas or serving specific functions
Figure 2.3

13. An Animal Cell
Figure 2.3
Figure 2.3

14. The Nucleus The largest structure in a cell
Surrounded by a double-layered nuclear envelope
Contains:
- Nuclear pores that allow movement of some molecules in and out
- Nucleolus, which is the site of ribosome production
- Chromosomes composed of DNA and proteins
Figure 2.3

15. The Nucleus
Figure 2.4
Figure 2.3
Figure 2.4

16. Secretion illustrates how organelles function together to coordinate the basic functions of life
Secretion – The Eukaryotic Production Line
Figure 2.5

17. Endoplasmic Reticulum (ER)
Interconnected membranous tubules & sacs
Winds from the nuclear envelope to the plasma membrane
Rough ER contains ribosomes and is involved in protein synthesis
Smooth ER does not contain ribosomes and is important in lipid synthesis
Figure 2.3

18. Golgi Apparatus Stack of flat membrane-enclosed sacs
Processing center that adds sugars forming glycoproteins and glycolipids
Site of final protein folding
Products are released into vesicles that bud off to the plasma membrane
Figure 2.3

19. Lysosomes
Membrane-bound sacs containing > 40 types of digestive enzymes
Degrade bacteria, cellular debris, and nutrients
Tay-Sachs is an inherited lysosomal storage disorder
Figure 2.3
Figure 2.6

20. Peroxisomes
Sacs with outer membranes studded with several types of enzymes that:
Detoxify compounds from free radicals
Break down lipids, rare biochemicals
Synthesize bile acids
Abundant in liver and kidney cells
Figure 2.3

21. Mitochondria Surrounded by two membranes
Site of ATP (energy) production
“powerhouse of cell”
Contain their own circular DNA
Human mitochondrial DNA is inherited only from the mother
Figure 2.7
Figure 2.3

22. Structures and Functions of Organelles
Table 2.1

23. Plasma Membrane Forms a selective barrier A phospholipid bilayer
- Phosphate end (hydrophilic)
- Fatty acid chains (hydrophobic)
Figure 2.8
Figure 2.3

24. Plasma Membrane Contains proteins, glycoproteins, and glycolipids
- Important to cell function and interactions
- May be receptors
- Form channels for ions
Figure 2.3
Figure 2.9

25. Faulty Ion Channels Cause Inherited Diseases
Sodium channels
- Mutations lead to absence or extreme pain
Potassium channels
- Mutations lead to impaired heart function and deafness
Chloride channels
- Mutations lead to cystic fibrosis
“Burning man syndrome” channels become hypersensitive, in response to exercise, increase in room temperature or just putting on one’s socks.
Salt trapped inside cells draws moisture and in thickens surrounding mucus.
Figure 2.3

26. Cytoskeleton A meshwork of protein rods and tubules
Figure 2.10
A meshwork of protein rods and tubules
Includes three major types of proteins
- Microtubules
- Microfilaments
- Intermediate filaments
Figure 2.3

27. Cytoskeleton Functions
Maintain cell shape
Connect cells to each other
Transport organelles and small molecules
Provide cell motility (some cell types)
Move chromosomes in cell division
Compose cilia and flagella
Figure 2.3

28. Abnormalities
Spherocytosis is a heredity defect in the cytoskeleton of the red blood cell. An abnormal cytoskeleton protein beneath the cell membrane and causes the red blood cells to balloon out, blocking narrow blood vessels in organs.

29. Cell Division and Death
Normal growth and development require an intricate interplay between the rates of two processes
Mitosis – Cell division
- Produces two somatic cells from one
Apoptosis – Cell death
- Precise genetically-programmed sequence
Figure 2.3

30. Figure 2.13
Figure 2.12

31. The Cell Cycle The sequence of events associated with cell division
Figure 2.14
G phase: Gap for growth
S phase: DNA synthesis
M phase: Mitosis (nuclear division)
Cytokinesis: Cell division
Figure 2.3

32. Stages of the Cell Cycle
Interphase
- Prepares for cell division
- Replicates DNA and subcellular structures
- Composed of
G1 – proteins, lipids, & carbs are produced
S – DNA and proteins are made
G2 – more proteins produced
- Cells may exit the cell cycle at G1 or enter G0, a dormant phase
Mitosis – Division of the nucleus
Cytokinesis – Division of the cytoplasm
Figure 2.3

33. Replication of Chromosomes
Chromosomes are replicated during S phase prior to mitosis
The result is two sister chromatids held together at the centromere
Figure 2.15
Figure 2.3

34. Mitosis Used for growth, repair, and replacement
Consists of a single division that produces two identical daughter cells
A continuous process divided into 4 phases
- Prophase
- Metaphase
- Anaphase
- Telophase
Figure 2.3

35. Mitosis in a Human Cell
Figure 2.15
Figure 2.16

36. Prophase Replicated chromosomes condense
Microtubules organize into a spindle
Nuclear envelope and nucleolus break down
Figure 2.3
Figure 2.16

37. Metaphase Chromosomes line up on the cell’s equator or metaphase plate
Spindle microtubules are attached to centromeres of chromosomes
Figure 2.3
Figure 2.16

38. Anaphase Centromeres divide
Chromatids separate and become independent chromosomes
- They move to opposite ends of the cell
Figure 2.3
Figure 2.16

39. Telophase Cell pinches in middle Chromosomes uncoil
Spindle disassembles
Nuclear envelope reforms
Figure 2.3
Figure 2.16

40. Cytokinesis
Cytoplasmic division occurs after nuclear division is complete
Organelles and macromolecules are distributed between the two daughter cells
Microfilament band contracts, separating the two cells
Figure 2.3

41. Mitosis Animation
Figure 2.3

42. Cell Cycle Control
Checkpoints ensure that mitotic events occur in the correct sequence
Internal and external factors are involved
Many types of cancer result from faulty checkpoints
Figure 2.3

43. Cell Cycle Control
Figure 2.17
Figure 2.16

44. Telomeres Located at the ends of the chromosomes
Cellular clock limits number of divisions based on shrinking telomeres, after about 50 divisions
Crowding, hormones, & growth factors are extracellular influences on mitosis
Sperm, eggs, bone marrow, and cancer cells produce telomerase that prevent shortening of telomeres
Why is this important?
Figure 2.3

45. Apoptosis Begins when a cell receives a “death signal”
Killer enzymes called caspases are activated
-Destroy cellular components
Phagocytes digest the remains
Figure 2.3

46. Mitosis and apotosis work together to form functional body
Programmed cell death is part of normal development
Figure 2.19
Mitosis and apotosis work together to form functional body
Cancer or other disorders can result from too much mitosis, too little apotosis
Figure 2.18

47. Stem Cells A stem cell divides by mitosis
- Produces daughter cells that retain the ability to divide and some that specialize
Progenitor cells do not have the capacity of self-renewal
Figure 2.3
Figure 2.22

48. Stem Cells
All cells in the human body descend from stem cells via mitosis and differentiation
Cells differentiate down cell lineages by differential gene expression
Stem cells are present throughout life and provide growth and repair
Figure 2.3

49. Figure 2.23
Figure 2.3

50. Stem Cells
Stem cells and progenitor cells are described in terms of their developmental potential
Totipotent – Can give rise to every cell type
Pluripotent – Have fewer possible fates
Multipotent – Have only a few fates
Figure 2.3

51. Stem Cells in Health Care
There are 3 general sources of human stem cells
1) Embryonic stem cells – Created in a lab dish using the inner cell mass (ICM) of an embryo
2) Induced pluripotent stem (iPS) cells – Somatic cells reprogrammed to differentiate into any of several cell types
3) Adult stem cells – Tissue-specific or somatic stem cells
Figure 2.3

52. Stem Cells in Health Care
Figure 2.24
Figure 2.24

53. Stem Cell Applications
Stem cells are being used in four basic ways
1) Discovery and development of drugs
2) Observing the earliest sign of disease
3) Treatment of disease via implants and transplants
4) Stimulating stem cells in the body via the introduction of reprogramming proteins
Figure 2.3

54. Stem Cell Applications
Figure 2.25
Figure 2.3