CELL BIOLOGY

Peng Xi

Peking University

Outline

Cell― Structure

― Cell process

Tissue― Morphology

― Function

Cell

Target that Biomedical optics study:― Cell( Including subcellular organelles)

― Tissue (Including organs and body)

Cell― In vivo 活体― Ex vivo 死体

Tissue― In situ 原位― In vivo 活体― Fixed

http://www.tokresource.org/tok_classes/biobiobio/biomenu/cell_theory/index.htm

Structure of cell

Plasma membrane

Cell wall― Prokaryotic cell

― Eukaryotic plant cell

Cytoplasm

Cytosol 胞液 Organelle

Nucleus

原核细胞

真核细胞

Plasma membrane 质膜

A semipermeable outer boundary of both prokaryotic and

eukaryotic cells. This outer membrane, about 4–5nm

thick, is a continuous sheet of a double layer (bilayer) of

long-chain molecules called phospholipids.

A phospholipid molecule has a long tail of alkyl 烷基chain, which is hydrophobic (repels water), and a

hydrophilic head (likes water) which carries a charge (and

is thus ionic).

Phospholipid molecules

spontaneously orient (or

self-organize) to form a

bilayer in which the

hydrophobic tails are

pointed inwards (shying

away from the outer

aqueous environment).

The hydrophilic, ionic

head groups are in the

exterior and are thus in

contact with the

surrounding aqueous

environment.

Cytoplasm 细胞质

Cytoplasm represents everything enclosed by the plasma

membrane, with the exclusion of the nucleus.

It is present in all cells where metabolic reactions occur.

Consists mainly of a viscous 粘性 fluid medium that

includes salts, sugars, lipids, vitamins, nucleotides, amino

acids, RNA, and proteins which contain the protein

filaments, actin microfilaments, microtubules, and

intermediate filaments.

Many of the functions for cell growth, metabolism, and

replication are carried out within the cytoplasm.

Cell skeleton 细胞骨架

Network of fibers composed of proteins

Three kinds:― Microtubule (25nm)

― Intermediate filaments (10nm)

― Actin filaments (8nm)

Cell skeleton 细胞骨架

Main functions:― Establish the cell shape

― Provide mechanical strength to the cell

― Perform muscle contraction

― Control changes in cell shape and thus produce locomotion

― Provide chromosome separation in mitosis （有丝分裂） and

meiosis （减数分裂）― Facilitate intracellular transport of organelles

Nucleus 细胞核

The nucleus is often called the control center

of the cell. It is the largest organelle in the cell,

usually spherical with a diameter of 4–10 μm,

and is separated from the cytoplasm by an

envelope consisting of an inner and an outer

membrane. All eukaryotic cells have a nucleus.

The nucleus contains DNA distributed among

structures called chromosomes 染色体 , which

determine the genetic makeup of the

organism. The chromosomal DNA is packaged

into chromatin fibers by association with an

equal mass of histone proteins 组蛋白 .

The nucleus contains openings (100nm across)

in its envelope called nuclear pores, which

allow the nuclear contents to communicate

with the cytosol. Ribosome 核糖体

Nucleus 细胞核

The inside of the nucleus also contains another

organelle called a nucleolus 核仁 , which is a

crescent-shaped 月牙形 structure that

produces ribosomes by forming RNA and

packaging it with ribosomal protein. The

nucleus is the site of replication of DNA and

transcription into RNA. In a eukaryotic cell,

the nucleus and the ribosomes work together

to synthesize proteins.

Ribosome 核糖体

Mitochondria 线粒体

Cell “power plant”

Shape: fat sausage, 0.5-1.5um wide and 3-10um long.

20% of the cytoplasmic volume

NADH + H+ + 3 ADP + 3 Pi + 1/2 O2 NAD+ + 4 H2O + 3 ATP

FADH2 + 3 ADP + 3 Pi + 1/2 O2 FAD + 4 H2O + 3 ATP

Endoplasmic reticulum(ER) 内质网

ER consists of flattened sheets,

sacs, and tubes of membranes

that extend throughout the

cytoplasm of eukaryotic cells and

enclose a large intracellular

space called lumen. There is a

continuum of the lumen between

membranes of the nuclear

envelope. The rough endoplastic

reticulum (rough ER) is close to

the nucleus, and is the site of

attachment of the ribosomes.

Endoplasmic reticulum(ER) 内质网

Ribosomes 核糖体 are small and dense structures, 20nm in diameter,

that are present in great numbers in the cell, mostly attached to the

surface of rough ER, but can float free in the cytoplasm. They are

manufactured in the nucleolus of the nucleus on a DNA template and

are then transported to the cytoplasm. They consist of two subunits of

RNA (a large, 50S, and a small, 30S) that are complexed with a set of

proteins.

Ribosomes are the sites of protein synthesis. The process of protein

synthesis uses a messenger RNA template.

The rough ER transitions into a smooth endoplastic reticulum

(smooth ER), which is generally more tubular and lacks attached

ribosomes.

The smooth ER is the primary site of synthesis of lipids and sugars

and contains degradative enzymes, which detoxify many organic

molecules.

Others

Glogi apparatus 高尔基体― Shipping and receiving dept. for protein

Lysosome 溶酶体― Bags of hydrolytic enzymes that are 0.2-0.5um

Peroxisome 过氧物酶体― Membrane bound vesicles containing oxidative enzymes

Chloroplast 叶绿体 (only in plant cell)― Site of photosynthesis

Types of cells

Epithelial cell 上皮细胞― Form sheets called epithelia to line the inner and outer surface of the

body. Most are squamous cells 鳞状细胞 .

Blood cell

Nerve cell (neuron)

Sensory cell

Germ cell 生殖细胞 Stem cell

Erythrocytes (Red blood cell)― 7-9um diameter, no nuclei

― Contain hemoglobin which can

bind O2

― 1cm cube blood: 5 billion RBC

Leucocyte (White blood cell)― WBC:RBC=1:1000

― Lymphocyte 淋巴细胞 • T cell: cell mediate immunity

• B cell: produce antibody

― Macrophages 巨噬细胞 and

neutrophils 中性白细胞

Thrombocyte (Platelet)― Produce specific substances for

blood coagulation

http://kids.britannica.com/elementary/art-88528/Blood-is-made-up-of-red-blood-cells-white-blood

Question: What kind of blood cell has to be diagnosed for

HIV infection?

http://www.thebody.com/content/art2494.html

HIV and T-cell (CD4)

Early in the course of the disease, the body can make more

CD4 cells to replace the ones that have been damaged by

HIV. Eventually, the body can't keep up and the number of

functioning T-cells decreases. As more and more CD4 cells

become damaged, the immune system becomes more and

more weakened. Eventually, the weakened immune system

leaves the body at risk for illness and infection.

http://aids.about.com/od/technicalquestions/f/cd4.htm

STEM CELLS….______ Inner cell mass becomes the baby

全能

桑椹胚

多能性

囊胚

内细胞团

Stem cell

The Nobel Prize in Physiology or Medicine 2012

The Nobel Prize in Physiology or Medicine 2012 was

awarded jointly to Sir John B. Gurdon and Shinya

Yamanaka "for the discovery that mature cells can be

reprogrammed to become pluripotent"

Cellular processes

Replication

Biosynthesis

Energy production

Signaling

Death

Transformation

Replication

Question: How a biological being can survive for

evolution?

Driving force in life: replicate for the continuing survival

of the species.

Cell Death

Death is a necessary part of life.

Apoptosis 细胞凋亡― Programmed Cell Death (suicide)

1. Cells infected with a virus

2. Cells of the immune systems

3. Cells with DNA damage

Cell killing― Cell death by injury, accidental cell death

― Mechanical damage or toxic chemicals

Cell that won’t regularly suicide: cancer cells

http://www.fitnesssutra.com/2010/09/13/sun-bath-and-its-importance-to-health/

Cell transformation

Permanent inheritable alteration of cell

Uptake and incorporation of foreign DNA― Virus

― Cancer causing agents such as mutagens 基因突变― Oncogenesis 肿瘤 properties

Cancer proliferation and screening

Cancer is different with normal cells in:• Cell metabolism;• Cell morphology.

Squamose cell cancer

Normal skinCarcinoma cells

http://tissupath.com.au/medical-student-subjects-skin/

http://networks.lww.com/pathology/blog/iow/pages/default.aspx

Histology: ex vivo, invasive

•Cannot evaluate the progress/cure effectiveness

•Trigger the cancer growth from benign to malign

Tissues

This part of ppt is originated from www.lavc.edu/instructor/watson_k/docs/Tissues.ppt 

Tissues

Definition: a group of closely associated cells that perform related functions and are similar in structure

Between cells: nonliving extracellular material

Four basic types of tissue…functionEpithelium…coveringConnective tissue…supportMuscle tissue…movementNervous tissue…control

Epithelia 上皮 (plural) Epithelium: sheet of cells that covers a body

surface or lines a body cavity; also form most of the body’s glands

Roles: as interfaces and as boundaries Functions:

Protection Absorption

Sensory reception Ion transport

Secretion Filtration

Formation of slippery surfaces for movement

Special characteristics of epithelia

Cellularity 多孔性 Specialized contacts 触体 Polarity

Free upper (apical) surface Lower (basal) surface contributing basal lamina to

basement membrane Support by connective tissue Avascular 无血管 but innervated 有神经

Without vessels With nerve endings

Regeneration 再生

Classification of epithelia

According to thickness“simple” - one cell layer“stratified” – more than one layer of cells

(which are named according to the shape of the cells in the apical layer)

According to shape“squamous” – wider than tall“cuboidal” – as tall as wide“columnar” - taller than wide

to protect

where diffusion is important

where tissues are involved in secretion and absorption: larger cells because of the machinery of production, packaging, and energy requirements

“ciliated” literally = eyelashes(see next page)

气管

Stratified: regenerate from below

Rare…

Rare…

Endothelium 内皮 A simple squamous

epithelium that lines the interior of the circulatory vessels and heart

Mesothelium 间皮

Simple squamous epithelium that lines the Peritoneal 腹膜 , pleural 胸膜 and pericardial 心包 cavities and covers the viscera 内脏

Glands 腺体 Epithelial cells form them Production & secretion of needed

substances Are aqueous (water-based) products The protein product is made in rough ER,

packed into secretory granules by Golgi apparatus, released from the cell by exocytosis 胞外分泌

Classification of glands

By where they release their productExocrine 外分泌 : external secretion onto body

surfaces (skin) or into body cavitiesEndocrine 内分泌 : secrete messenger

molecules (hormones) which are carried by blood to target organs; “ductless” glands By whether they are unicellular or multicellular

Exocrine glands 外分泌腺unicellular or multicellular

Unicellular: goblet cell 杯状细胞 scattered within epithelial lining of intestines and respiratory tubes 呼吸道

Product: mucin 粘蛋白mucus 黏液 is mucin & water

Multicellular exocrine glands

Epithelium-walled

duct and a

secretory unit

Examples of exocrine gland products

Many types of mucus 黏液 secreting glands

Sweat glands of skin Oil glands of skin Salivary glands of mouth 唾液 Liver (bile) 胆汁 Pancreas (digestive enzymes) 胰脏 Mammary glands (milk) 乳腺

Endocrine glands

Ductless glands

Release hormones into extracellular spaceHormones are messenger molecules

Hormones enter blood and travel to specific target organs

Epithelial surface features

Lateral surface 水平面Adhesion proteinsTongue and groove wavy contoursCell junctions: see next slide

Basal surface 基底面Basal lamina: noncellular sheet of protein

together with reticular fibers form basement membrane

Apical surface 顶面

Cell Junctions Tight junctions

So close that are sometimes impermeable

Adherent junctions 粘附连接 Transmembrane linker

proteins Desmosomes 桥粒

Anchoring junctions Filaments anchor to the

opposite side Gap junctions

Allow small molecules to move between cells

Apical surface features

Microvilli 微绒毛 – maximize surface areaFingerlike extensions of the plasma

membrane of apical epithelial cellsOn moist and mucus secreting epitheliumLongest on epithelia that absorb nutrients

(small intestine) or transport ions (kidneys)

Four basic types of tissue

EpitheliumConnective tissue

Connective tissue proper (examples: fat tissue, fibrous tissue of ligaments)

Cartilage Bone Blood

Muscle tissueNervous tissue

Classes of Connective Tissue: note the cell types and great variety of subclasses

成纤维细胞 成软骨细胞 造骨细胞 成血干细胞

间叶细胞

Connective Tissue Originate from embryonic tissue called

mesenchyme 间叶细胞 Most diverse and abundant type of tissue Many subclasses (see previous slide) Function: to protect, support and bind together

other tissues Bones, ligaments, tendons Areolar cushions; adipose insulates and is food

source Blood cells replenished; body tissues repaired

Cells separated from one another by large amount of nonliving extracellular matrix

Extracellular Matrix explained

Nonliving material between cells Produced by the cells and then extruded Responsible for the strength Two components

1. Ground substance Of fluid, adhesion proteins, proteoglycans 蛋白多

糖 Liquid, semisolid, gel-like or very hard

2. Fibers: collagen, elastic or reticular

Basic functions of connective tissue reviewed

Support and binding of other tissues Holding body fluids Defending the body against infection

macrophages, plasma cells, mast cells, WBCs Storing nutrients as fat

Classes of Connective Tissue

*

间叶细胞

Mesenchyme 间质

aerolar tissue粘贴组织

lamina propria 黏膜肌层

collagen, elastin and reticular fibers

Adipose 脂肪

Reticular 网状层

*

Classes of Connective Tissue

aponeurosis 腱膜

*

Classes of Connective Tissue

腔隙

肋软骨

透明

软骨细胞

Classes of Connective Tissue

*

Classes of Connective Tissue

*

Membranes that combine epithelial sheets plus underlying connective tissue proper (see next slide)

Cutaneous membranes Skin: epidermis and dermis

Mucous membranes, or mucosa Lines every hollow internal organ that opens to the

outside of the body Serous membranes, or serosa

Slippery membranes lining the pleural, pericardial and peritoneal cavities

The fluid formed on the surfaces is called a transudate Synovial membranes

Line joints

(a) Cutaneous membrane

(b) Mucous membrane

(c) Serous membrane

Four basic types of tissue

EpitheliumConnective tissueMuscle tissue

Skeletal Cardiac Smooth

Nervous tissue

Four basic types of tissue

EpitheliumConnective tissueMuscle tissueNervous tissue

NeuronsSupporting cells

Summary

All living creatures are made up of cells.

Biological systems are classified as viruses (non-self-

replicating), prokaryotes (no well-defined nucleus), and

eukaryotes (well-organized cell and nucleus).

Living systems are aggregates of water, amino acids,

carbohydrates, fatty acids, ions, and other

macromolecules called biopolymers (e.g., DNA, RNA, and

proteins).

Cells undergo differentiation to form different types of

cells and as-semble to form tissues, which organize to

form organs with different functions. Various organs

integrate to form an organism.

Summary

A plasma membrane consists of a structure lipid bilayer that forms a

semipermeable boundary around the cell. The membrane controls the

transport of food, water, ions, and signals.

The interior contents of a cell, enclosed by the membrane, consists of

various organelles (compartments) such as the cytoplasm,

cytoskeleton, nucleus, mitochondria, endosplasmic reticulum (ER),

Golgi apparatus, lysosomes, and peroxisomes. Plant cells have an

additional organelle, called the chloroplast .

Cytoplasm consists of the entire contents of a cell (except the nucleus)

enclosed by a membrane. Cytoplasm forms the center of activities

such as cell growth, metabolism, and replication

Summary

Important cellular processes are: (i) cell replication to

produce DNA and, subsequently, new cells; (ii) cell

biosynthesis by a process of transcription to produce RNA

and a process of translation to synthesize protein; (iii) cell

energy production in a usable form; (iv) cell signaling to

initiate processes in adjacent and distant cells; (v) cell

death by programmed cell death and death due to injury;

and (vi) cell transformation that produces a tumor.

The constituents of a tissue are: (i) various cells; (ii) cell-adhesion

molecules which bind cells to one another; (iii) extracellular matrix

filling the space between cells; and (iv) the cell junctions.

The extracellular matrix helps to bind the cell, acts as a reservoir for

hormones controlling cell growth and differentiation, and provides a

lattice through which cells can move.

Cell junctions stabilize cell–cell infrastructure and facilitate

communication between neighboring cells.

Tumors consist of cells with structural changes produced by

transformation that show aberration in the normal behavior.

Cancer is a special type of tumor that exhibits much more rapid

multiplication (proliferation) of cells compared to normal cells.

Thank you!