CELLS & TISSUES

Molecules of LifeChapter 2

MOLECULES OF LIFE⦿ Carbohydrates

◼ “Saccharides” – sugar and starch molecules◼ Simple Carbs – made of one or two subunits

• Monosaccharide - glucose • Disaccharide – made of 2 monosaccharides -

sucrose◼ Simple sugars join together to make complex

carbohydrates◼ Main function: serve as source of chemical

energy or fuel• Body utilizes this fuel to make ATP

MOLECULES OF LIFE⦿ Proteins◼ Made of chains of amino acids

• 20 common amino acids ● Peptides & polypeptides

◼ Form the structure of cells◼ Enzymes – catalyze specific biological

reactions◼ Others act as carriers – hemoglobin

MOLECULES OF LIFE

⦿ Lipids◼ Fats and oils◼ Do not dissolve well in water or blood

• Special proteins help carry lipids in the blood

◼ Not as big as proteins or carbs◼ Stored fat helps sustain prolonged exercise◼ Also helps during recovery from exercise ◼ Fatty acids, glycerides, phospholipids, steroids

CHECK YOUR UNDERSTANDING

⦿ What is the main function of carbs?⦿ What are the differences between simple and

complex carbs?⦿ What are the 3 functions of proteins in our

body?⦿ Why is it beneficial for our bodies to store

excess calories as fat?

NUCLEIC ACIDS⦿ Information carrying molecules in cells

◼ Two kinds found in cells: • Ribonucleic acid (RNA)• Deoxyribonucleic acid (DNA)

⦿ Subunits = nucleotides ⦿ Each made of a phosphate group, a sugar

group, and a nitrogenous base

NUCLEOTIDES⦿ 5 different kinds

◼ Adenine, guanine, cytosine, thymine, uracil

⦿ DNA is made of nucleotides containing ◼ A, G, C, T

⦿ RNA is made of nucleotides containing◼ A, G, C, U

DNA⦿ Two nucleotide chains coil

around each other to form a double helix

⦿ Base pairs◼ A & T, C & G

⦿ Base pairs are joined by hydrogen bonds ◼ DNA has ability to “unzip”

⦿ Sugar phosphate backbone are joined by covalent bonds◼ Stronger than hydrogen bonds

CHROMOSOMES ⦿ One DNA molecule and the proteins around it⦿ Almost every human cell has 46

◼ 23 from each parent

⦿ 22 pairs of similar chromosomes ◼ Plus one X Y pair in males◼ Two X chromosomes in females

⦿ 2 exceptions:◼ Sperm cells and egg cells (have 23)◼ Red blood cells – do not have nuclei or

chromosomes

RNA⦿ Polymer of nucleotides (like DNA)⦿ Base pairs

◼ A & U, C & G ⦿ 4 types

◼ mRNA• Information carrier in manufacture of proteins

◼ tRNA• Assists in manufacture of proteins

◼ rRNA• Forms ribosomes (large enzymes that act as catalysts

for protein synthesis)◼ Regulatory RNA

• Regulates which proteins are produced

CHECK YOUR UNDERSTANDING

⦿ What are nucleic acids?⦿ How do the nucleotides in DNA and RNA

differ?⦿ Why is it important that DNA has the ability

to “unzip”?⦿ How many chromosomes do most human cells

have?

ATP⦿ Adenosine triphosphate⦿ Composed of:

◼ adenine base, sugar, and three phosphate groups

⦿ Common energy source ⦿ Chemical potential energy is stored in bonds

between the phosphates

WATER⦿ All life is water based⦿ 2/3 of the mass of the human body⦿ Water forms hydrogen bonds⦿ Responsible for:

• High heat capacity• High boiling point• Solvent properties

BELL WORK⦿ Materials Needed: bell work notebook,

writing utensil, and A&P book. Turn in Lesson 2.1 homework.

⦿ Date?⦿ What is biochemistry? Why is it important in

the study of A&P?⦿ What kind of bonds join base pairs in DNA?

What do these bonds allow DNA to do?

CELLS⦿ Surrounded by extracellular fluid⦿ Plasma membrane

◼ Defines the outer shell of a cell ◼ Keeps the inside in and outside out◼ Controls what passes through

⦿ Cytoplasm◼ Inside the membrane◼ Contains everything except the nucleus

⦿ Cytoskleteton ◼ Defines the shape of the cell◼ Gives it mechanical strength

CELLS⦿ Mitochondria

◼ Make ATP◼ Universal carrier of energy within cells◼ “Powerhouse”

⦿ Golgi Apparatus◼ Set of membranous discs◼ Produces spheres called vesicles

• Vesicles deliver proteins to the plasma membrane

CELLS⦿ Ribosomes

◼ Very large enzymes • Made of RNA and proteins

⦿ Endoplasmic Reticulum◼ Network of membranes in the cytoplasm◼ Rough and smooth ER

• Rough – protein production and modification• Smooth – “replacement” membrane is made● Site of steroid hormone production in cells or

reproductive organs

LIFE CYCLE OF A CELL⦿ Interphase

◼ 3 subphases• Gap phase (G1)● Cell maintenance and growth

• Synthetic phase● DNA synthesis

• Gap phase (G2)● Cell maintenance, growth, and preparation for

division

⦿ Some cells will never divide (red blood cells in brain)◼ These cells are in phase G0

LIFE CYCLE OF A CELL⦿ Mitotic Phase

◼ Broken into mitosis and cytokinesis◼ Mitosis

• Division of a cell nucleus and chromosomes into two nuclei

◼ Cytokinesis• Division of the cytoplasm

⦿ Mitotic Cell Division◼ Process by which a single fertilized egg cell

develops into an adult made of trillions of cells

LIFE CYCLE OF A CELL⦿ Mitosis is broken down into 4 phases:

◼ Prophase• chromatin condenses to form chromosomes • Spindle fibers form

◼ Metaphase• Spindle fibers lock onto chromosomes and are

positioned along the midline of the cell

◼ Anaphase• Separase cuts each centromere in half – 46 chromatids

go to one side, 46 go to the other

◼ Telephase• Chromosomes decondense and a new nuclear

membrane forms around the DNA

HISTOLOGY ⦿ Study of tissues⦿ 4 main types of tissue

◼ Epithelial ◼ Connective◼ Muscle◼ Nervous

⦿ Each tissue has its own subtypes

EPITHELIAL TISSUE⦿ Includes epithelia and glands⦿ Epithelia

◼ Cover the body & line cavities within the body

⦿ Glands◼ Secrete chemicals to the outside world or within

the body

⦿ Epithelial tissue functions◼ Protect the body from physical damage◼ Control what substances enter and leave body◼ Provide sensory information◼ Secret various substances

EPITHELIAL TISSUE⦿ Classified according to layers and shape

CONNECTIVE TISSUE⦿ Found throughout the body

◼ Protects internal organs◼ Gives strength to resist external forces (gravity)◼ Maintains proper shape of organs◼ Provides framework on which muscle can pull

• Allows movement

⦿ 4 major classes◼ Connective tissue proper◼ Cartilage◼ Bone◼ Blood

LOOSE CONNECTIVE TISSUE

DENSE CONNECTIVE TISSUE

CARTILAGE

BONE

BLOOD

MUSCLE TISSUE

NERVE TISSUE