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Structure and Function of Cells and Tissues

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Title: Structure and Function of Cells and Tissues


1
LATG Chapters 6 - 7
Cells Tissues Organic Chemistry, Biochemistry
and Infectious Diseases
2
Cells
Prokaryotic bacteria, blue-green
algae Eukaryotic plants, animals, fungi, many
unicellular organisms Both cell types have DNA,
are membrane bound, have ribosomes, have similar
basic metabolism Eukaryotic cells larger
(1000X), more complex DNA, have a nuclear and
organelle membranes, have cytoskeleton
3
Cells
4
Cells
5
Cells
6
Cells
Plasma membrane proteins and lipids that allows
fat soluble molecules to penetrate easily but
prohibits water soluble molecules from going
across without facilitated diffusion or active
transport
7
Cells
Within the lipid bilayer are many types of
proteins cell receptors, transport proteins,
enzymes
8
Cells
Lipid soluble substances can enter and leave the
cell by passive diffusion following concentration
gradients
9
Cells
Substances can also cross the membranes without
energy expenditure via osmosis solvent
molecules (usually H20) move across a
semi-permeable membrane due to osmotic pressure
Isotonic
Hypotonic Hypertonic
10
Cells
Facilitated or carrier-mediated diffusion occurs
with molecules that are not normally fat soluble,
but become so when combined with a carrier
substance allowing entry or exit from the cell
11
Cells
Active transport is the movement of substances
against a concentration or electrochemical
gradient and usually requires energy expenditure
by the cell
12
Cells
13
Cells
Large molecules or entire cells can enter the
host cell by endocytosis either via pinocytosis
or phagocytosis and exit the cell via exocytosis
14
Cells
The nucleus is made up of DNA deoxyribonucleic
acid, and RNA ribonucleic acid, and is involved
in cell reproduction and metabolic
activities Nucleoli may be present in resting
cells and are sites of ribosomal RNA
production The nucleus is surrounded by a
nuclear membrane containing pores and continuous
with the endoplasmic reticulum in some areas
15
Cells
DNA is made up of chains of nucleotides and form
the basic element of genes which determine all of
our inherited characteristics Nucleotides
consist of a sugar molecule deoxyribose bonded
with a phosphate group and a nitrogenous
base Nitrogenous bases can be either adenine,
guanine, cytosine or thymine
16
Cells
DNA is usually found in double, complementary
strands that are held together by hydrogen bonds
between the nitrogenous bases Adenine binds with
thymine, cytosine binds with guanine When the
DNA is not replicating, these strands form a
spiral or double helix
17
Cells
During DNA replication, the complementary strands
separate and enzymes known as polymerases add
new bases that are identical to the
original opposite strand
18
Cells
After the DNA replicates itself, the cell is
ready to divide. At this point there is
condensing down of the DNA in the nucleus from
the loosely arranged chromatin into distinct
chromosomes.
19
Cells
Mitosis, or cell division, produces two
genetically identical cells
20
Cells
DNA replicates itself, but also can produce RNA
in a process called transcription. The RNA
leaves the nucleus as a single strand DNA areas
in the nucleolus produce ribosomal RNA or
rRNA Other RNA types are messenger (mRNA) and
transfer (tRNA)
21
Cells
rRNA combines with proteins to form ribosomes
Ribosomes then read the mRNA to synthesize
proteins from amino acids in a process called
translation
22
Cells
Translation uses rRNA, mRNA, and tRNA to
create protein molecules from amino acids
23
Cells
Translation occurs on the surface of the
endoplasmic reticulum, a membrane bound organelle
in the cells cytoplasm
24
Cells
Electron microscope pictures showing the rough ER
and ribosomes producing proteins
25
Cells
There are other organelles found within the
cytoplasm
The Golgi apparatus is found close to the nucleus
and endoplasmic reticulum. Its job is to
receive, sort and process the biomolecules it
receives from the ER and resecrete them.
26
Cells
Mitochondria are used for aerobic respiration and
production of energy (ATP) for the for proper
functioning of the cells metabolic processes.
27
Cells
Lysosomes are full of enzymes that break down
fats, protein and carbohydrates into their
smallest elements to be used by the mitochondria
for energy.
Vacuoles are often found in the cytoplasm and
assist in getting rid of water and waste products
from the cell
28
Cells
Microtubules provide support for the cell known
as the cytoskeleton to help the cell keep its
shape and control flow of elements through the
cell.
Centrioles are bundles of microtubules
that assist in separation of the
chromosomes during mitosis when they form
into mitotic spindles.
Microtubules also make up cilia and flagella that
are hair-like surface projections used to move
the cells themselves or material around the
outside the cells.
29
Tissues
Cells bound together and serving a specific
function are called tissues and include
epithelium, connective tissue, muscle tissue, and
nerve tissue.
Epithelium consists of sheets of cells that have
a basal lamina and an unattached or free edge.
It is typically found lining cavities, blood
vessels, gland ducts and hollow organs.
30
Tissues
Epithelium serves different functions depending
on its type and location but may be for
protection, absorption, secretion or facilitate
movement of substances over its free surface.
31
Tissues
Connective tissue is found throughout the body
and contains a variety of different cell types,
depending on its location.
Dense and loose connective tissue contains
fibroblasts and collagen fibers which provide
elasticity to the tissue.
32
Tissues
33
Tissues
Adipose tissue contains adipocytes which store
fat for metabolism and is primarily white.
Brown fat is in many species but the greatest
amount is found in species that hibernate and it
is thought to have a role in maintaining body
temperature by producing heat.
34
Tissues
Cartilage contains chondrocytes that are embedded
in a semi-rigid matrix. The number of fibers and
density of the matrix determines whether it is
hyaline cartilage, elastic cartilage, or
fibrocartilage.
35
Tissues
Bone is made up of osteocytes and ground
substance that consists of calcium phosphate.
The ends of long bones contain spongy or
cancellous bone while the shaft is compact bone
that surrounds the medullary cavity containing
the bone marrow.
36
Tissues
The cells found within connective tissue can be
fixed as seen with fibroblasts, chondrocytes,
osteocytes, and adipose cells. They can also be
wandering, usually coming from the blood, as seen
with eosinophils, neutrophils, lymphocytes,
monocytes, and mast cells.
37
Tissues
Muscle cells can either be smooth or striated,
depending on their function and appearance under
a microscope. Smooth muscle is found in most of
the our internal organs and exhibits involuntary
rhythmic and tonic contractions.
38
Tissues
Striated muscle can be either skeletal muscle,
that contracts voluntarily, or cardiac muscle
that contracts involuntarily.
39
Tissues
Nerve tissue is made up of neurons that are cells
characterized by a nucleated cell body,
dendrites, and an axon. Nerves respond to
stimuli by polarizing and depolarizing by varying
the concentration of sodium and potassium ions
inside the cell.
40
Tissues
Many nerves are covered with a myelin sheath that
speeds the conduction of the impulses down the
axon. The myelin is made from part of an
oligodendrocyte cell that wraps around the axon
and has gaps in it called nodes of Ranvier.
41
Tissues
The axons end either in synapses with other nerve
cells, or in motor end plates, innervating muscle
cells. The end releases neurotransmitters which
are chemicals that stimulate the next nerve or
muscle to respond.
42
Organic Chemistry, Biochemistry and Infectious
Diseases
  • Chapter 7

43
Biochemistry
  • The study of chemistry within living organisms
  • Inorganic molecules-water, sodium, potassium,
    calcium--molecules without carbon
  • Organic molecules-carbohydrates, lipids,
    proteins--molecules with carbon

44
Carbohydrates
  • The sugar family of molecules
  • Found as mono-, di- and polysaccharides
  • Used as energy source, supportive structures and
    nucleic acids

45
Monosaccharides
  • Glucose--the most common simple sugar found in
    biological systems
  • Provides energy for all body systems
  • Only source of energy for central nervous system
  • Galactose and fructose are other simple sugars
    commonly found

46
Disaccharides
  • Molecules made up of two simple sugars
  • Sucrose, maltose and lactose are two commonly
    found disaccarhides
  • Both mono- and disaccharides are known as simple
    sugars

47
Polysaccarhides
  • Complex molecules made up of many (sometimes
    thousands) simple sugars
  • Starch, cellulose and glycogen are the majors
    forms in animal and plant life
  • Glycogen is the major storage form for sugars in
    the mammalian body, primarily in muscle and liver

48
Lipids
  • Fatty molecules with multiple functions within
    the mammalian body
  • Energy storage
  • Protection
  • Insulation
  • Cell membranes

49
Lipids
  • Major forms are
  • Fatty acids
  • Triglycerides
  • Steroids

50
Fatty Acids
  • The building blocks of most lipids
  • Classified as saturated and unsaturated fatty
    acids
  • Some of the unsaturated fatty acids are
    classified as essential--can not be made by the
    body

51
Triglycerides
  • Larger lipid molecule composed of three fatty
    acids attached to one glycerol molecule
  • Primary energy storage in the body

52
Steroids
  • Another type of lipid important in hormonal
    balance
  • Some steroids
  • cholesterol
  • cortisol
  • testosterone
  • estrogen
  • Vitamin D

53
Proteins
  • Made up of chains of amino acids
  • Twenty amino acids are known
  • Ten of these are essential
  • These 20 amino acids combine to form over 35,000
    proteins during a mammals lifetime

54
Protein Function
  • Structure--collagen
  • Enzymes--lipase
  • Regulatory--G proteins
  • Transport--hemoglobin
  • Protective--immunoglobulins
  • Hormones--insulin
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