Cells bds

The Cell

THE CELL

Cell membrane

protective covering that surrounds the cell. Maintains cell shape Selectively permeable. Ingestion by the cells (endocytosis) Excretion by the cells (exocytosis) Takes part in cell locomotion Helps in attachment of the cells Fluid in nature; not solid

Functions of cell membrane

Functions of cell membrane

Composition of cell membrane

Phosopholipid 25% Proteins 55% Cholesterol 13% Carbohydrates 3%

Cell membrane structure

Phospholipid bilayer: The heads of the lipids

are hydrophilic (water loving)

The tails are hydrophobic (water fearing).

Proteins: Integral; act as *channels (pores)

*carriers

*enzymes Peripheral; act as enzymes

Cholesterol

Membrane CHO (Glycocalyx) Glycoproteins / Glycolipids Gives negative charge to the cell Helps in attaching cells one to another Act as receptors

Cytoplasm: Structure: gel-like material found inside the cell,

made of water, salts, and organic materials. Function: holds the organelles, keeps them

separate

Cell Organelles

Mitochondria: “powerhouse” of the cell Self replicative Structure: two lipid bilayer membranes

outer membrane inner membrane – shelves with attached oxidative

enzymes

Matrix; contains necessary enzymes Function: transform the energy in food to energy

the cell can use to drive chemical reactions.

Mitochondria

Formation of ATP

Uses of ATP

Cell Organelles

Endoplasmic Reticulum: Structure: tubular & flat vesicular str Interconnected with one another made of lipid bilayer along with protein Endoplasmic matrix Location: located next to the nuclear membrane

and connected to it Functions:

Conduction Metabolism

Types of ER

Smooth ER: does not contain ribosomes, makes lipids, transports proteins Drugs detoxification Contain enzymes for glycogen breakdown

Rough ER: contains ribosomes makes proteins

Cell Organelles

Golgi Body: Structure: 4 or more stacked layers of thin, flat enclosed

vesicles Location: near the nucleus Function: packages proteins from the ER Synthesize certain CHO

hyaluronic acid & chondroitin sulfate

Lysosomes/ secretory vesicles distribute them around or outside of the cell.

Prominent in secretory cells

Formation of proteins, lipids & vesicles from ER & GA

Cell Organelles

Ribosomes: Structure:

made of RNA and proteins

Function: produce proteins

Location: Free in cytosol attached to the endoplasmic reticulum.

Lysosomes

Formed from Golgi apparatus Structure:

lipid bilayer Sac filled with enzymes Hydrolases Compound + water

Proteins………………. a.a Glycogen……………...Glucose Lipids…………………..Fatty acid & glycerol

Lysosomes

Intracellular digestive system Damaged cellular str. Heat, cold, chemicals Autolysis Food particles phagocytic & pinocytic vesicles Bacteria Tissue regression Lack of activity in a tissue causes the lysosomes to

increase their activity

Lysosomes

Bactericidal agents Lysozymes

Dissolve the bacterial cell membrane Lysoferrin

Binds iron Acid

Activates hydrolases & inactivates bacterial metabolism

Peroxysomes

Formed by self replication / SER Intracellular digestive system Oxidize poisonous subs. as alcohol Enzymes:

Oxidases Oxygen + Hydrogen = Hydrogen peroxide

Catalases

Nucleus

Control center of the cell Contain DNA (genes)

Protein synthesis Reproduction

Nuclear envelope Double layer Outer memb continuous with ER Nuclear pores

Nucleoli No membrane RNA and proteins

Structure of nucleus

Cell Organelles

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Ameboid movement

Ameboid movement

Ameboid movement

Movement of entire cells in relation to its surroundings

Involves pseudopodium and ATP Mechanism

formation of new cell membrane & exocytosis at one end

Attachment of pseudopodium to tissues Receptor proteins

Absorption of the membrane & endocytosis in mid & rear portions

Detachment of receptor proteins

Ameboid movement

Cells that exhibit ameboid motion WBC Fibroblasts Embryonic cells

Control of ameboid motion Chemotaxis

Positive Negative

Genetic control of cell functions

DNA structure

Nucleotides Phosphoric acid Sugar deoxyribose Nitrogenous bases

Purine (adenine, guanine) Pyrimidines (thymine, cytosine)

DNA structure

Significance of DNA

Controls formation of proteins By “Genetic code” DNA code is transferred to an RNA code

(transcription)

Types of RNA

mRNA carries the code to cytoplasm in the form of

codons complementary to DNA code tRNA

transports activated amino acids to ribosomes Triplets of bases on tRNA that allows it to

recognize a specific codon is anticodon rRNA

forms ribosomes; str. On which protein molecules are assembled

Transcription

Temporary separation of DNA strand (RNA Polymerase enzyme)

DNA code causes formation of complementary RNA codes (codons)

DNA code

Protein synthesis

Code successive “triplets” of DNA bases It controls the sequence of a.a in a protein

molecule to be synthesized in cell Transcription

mRNA is formed containing codons which are complementary to the DNA code

process of transferring the genetic code to the RNA

Mutation

Translation Definition

Formation of proteins on the ribosomes Mechanism

mRNA travels thru ribosomes Ribosomes read the codons tRNA transports a.a Protein molecule is formed

Movement thru the Cell Membrane

Remember: The cell membrane provides support and

protection for the cell. The cell membrane is made of a lipid bilayer that

is selectively permeable. The lipid bilayer contains hydrophilic heads and

hydrophobic tails. Proteins in the bilayer help materials pass into and out of the cell.

Movement thru the Cell Membrane: Diffusion

Diffusion is the process of cells moving from areas of high concentration to areas of low concentration. Remember the scent diffusion lab from 7th

grade? Occurs because molecules are constantly

moving. This random movement causes the molecules to

become evenly spread out.


Molecules diffuse (move from high to low concentration) until the molecules are evenly spread out. This is called equilibrium. Diffusion doesn’t stop at equilibrium, the

molecules just move in equal numbers. If one molecule enters an area, another molecule leaves.


Cells use diffusion to get substances into and out of the cell. Example: During photosynthesis, oxygen is

produced inside the cell. When this happens the concentration of oxygen becomes higher inside the cell than outside and oxygen diffuses out of the cell.

Movement thru the Cell Membrane: Osmosis

Osmosis is the diffusion of water through a membrane. Water moves into an area with low

concentrations and out of areas with high concentrations.

Both diffusion and osmosis are forms of passive transport (they require no energy)

Movement thru the Cell Membrane: Active Transport

materials move from low concentration to high concentration. requires energy!

Active transport Endocytosis: moving a particle into the cell

Phagocytosis Pinocytosis

Exocytosis: moving a particle from inside the cell to outside.

Mec hanism of pinocytosis

Movement thru the Cell Membrane: Active Transport

Endocytosis Exocytosis

Cell Growth and Division

Multicellular organisms grow because cell division increases the number of cells in them.

Cells become specialized during the development of an organism.

Cells that are damaged or worn out are replaced by cell division.

Cell Growth and Division: The Cell Cycle

Interphase: The part of the cell cycle when the cell is not dividing. This is the longest phase in the cell cycle. Cells grow and go about their daily routines in

this part of the cycle. DNA (genetic material) replicates.


Mitosis: the part of the cell cycle where the nucleus divides. Occurs in non-reproductive cells and produces exact copies of the parent cell. Prophase: The chromosomes condense Metaphase: The chromosomes line up in the

middle of the cell. Anaphase: The chromosomes separate and are

pulled to either end of the cell. Telophase: The new nuclear membrane forms. Cytokinesis: The cell splits in half.



Meiosis: The cell division that takes place within reproductive cells. Produces cells that only have one pair of

chromosomes. Meiosis produces egg and sperm cells.

Before meiosis begins, the chromosomes from the parent cell are copied.


Meiosis I: Pairs of chromosomes separate Prophase I: Chromosomes pair up Metaphase I: The chromosome pairs line up in

the middle of the cell. Anaphase I: Chromosome pairs are pulled apart

to opposite ends of the cell Telophase I: A new cell membrane forms

around the chromosomes. Cytokinesis: The cell splits into two daughter

cells


Meiosis II: Chromosomes separate Prophase II: In each daughter cell, there are two

copies of a chromosome. Metaphase II: Each chromosome in each

daughter cell lines up in the middle of the cell. Anaphase II: Each chromosome in each

daughter cell is pulled apart to opposite ends of the cells.

Telophase II: A new cell membrane forms, splitting each daughter cell into two new cells.

Cytokinesis: The cells divide into four new cells.

Cells and Energy: Respiration

Most chemical reactions that take place in cells require an energy source. Mitochondria in both plant and animal cells

release this energy through respiration. Respiration is the process by which oxygen (O2)

is combined with food (sugar) to release energy. Before respiration can occur in the mitochondria,

sugar in the cytoplasm is broken down. This releases a small amount of energy.


If oxygen is not present in the environment, anaerobic respiration takes place. Fermentation: the process of cells releasing

energy without oxygen. There are two types of fermentation:

Alcoholic fermentation Lactic Acid fermentation


If oxygen is present in the environment, aerobic respiration can occur. After sugar in the cytoplasm is broken down, the

smaller pieces travel to the mitochondria and are broken down even more. This produces energy, called ATP (adenosine triphosphate).

Oxygen also enters the mitochondria and combines hydrogen to produce water.

Glucose + Oxygen Energy + Water + CO2

Cells and Energy: Photosynthesis

Plant cells gain energy through the process of photosynthesis. Photosynthesis takes place in chloroplasts.

Chloroplasts contain chlorophyll, the green pigment that captures sunlight for the plant.

Carbon dioxide (CO2) and water enter the chloroplasts while the chlorophyll captures sunlight.

The energy from the sunlight changes the CO2 and water into oxygen and sugar.

CO2 + Water + Energy Oxygen + Sugar

Technology

Cells bds