Functions of the cytoplasm
Give cell its shape Transport medium for dissolved substances Storage area for water insoluble substances Storage and circulation of substances within cell
Cell membrane (plasmalemma)
Fluid mosaic model Phospholipid bilayer Protein molecules embedded into the two phospholipid layers Provide support and flexibility
Functions of the cell membrane
Controls the movement of substances in and out of the cell Respiration (dissolved gases enter) and nutrients enter the cell Excretion Secretion
Diffusion
Movement of molecules from an area of higher concentration to an area of lower concentration until the concentration in both regions are the same
passive transport
Osmosis
The diffusion of water molecules from an area of high concentration to a low concentration across a selectively permeable membrane
Flaccid
Condition between turgid and plasmolyzed when a cell is placed in an isotonic solution
Turgid
Cell has reached maximum tension
Active transport
Molecules move from an area of low concentration to an area of high concentration, they move against the concentration gradient
Function of Nucleus
Contains chromatin network which contains hereditary information in DNA Contains information that controls all metabolic processes Nuclear pores allow certain substances in and out Makes ribosomes
Chromatin Network
Long threads of chromosomes folded and packed loosely
DNA
Two long strands of genetic information made of sugars, phosphates and nitrogenous bases. Formed in a double helix
Replicated chromosome
Contain the genetic information of the cell
Chromosome
Strand of DNA twisted around a backbone of proteins Thread like structures found in the nucleus
DNA replication
The process during which a DNA molecule makes an identical replica of itself
Haploid
One full set of chromosomes that includes a single copy of each gene.
Diploid
Two sets of chromosomes that include a double copy of each gene.
Mitosis
The process of cell division where two new identical diploid "daughter" cells are formed from diploid "mother" cell.
Role of mitosis
Development and growth Asexual reproduction Cell replacement Replacement of damaged tissues
Location of mitosis
Any living diploid cell
Stem cells
At growing points at the tip of roots and stems
Specialized tissue called Cambium
Stages in the cell cycle
Interphase - cell grows and replicates its DNA Mitotic phase - cell divides and transfers one copy of its DNA to two identical cells
Interphase
Period between two consecutive cell divisions Cell growth and DNA replication takes place Extra organelles formed
Events in prophase
Nuclear membrane and nucleolus disappear Chromatin network shortens and thickens to form individual chromosomes Centrioles separate and move to opposite poles of cell, spindle fibre forms between them
Events in Metaphase
Spindle enlarges Cytoplasmic threads pull double-threaded chromosomes to the 'equator' of the cell
Events in Anaphase
Centromere of each chromosome divides into two The two chromatids separate (kyrokinesis) Spindle fibre contracts and pulls chromatids to opposite poles
Events in Telophase
Chromosomes arrange themselves at the poles Spindle fibre disappears Cytoplasm divides (cytokinesis) into two daughter cells Nuclear membrane forms around each group of chromosomes at each pole and a nucleolus forms
Cancer
Result of uncontrolled cell division in the body
Malignant cancer cells
Able to invade tissues and spread to other parts of the body
Metastasis
The spread of cancer cells to locations distant from their original site.
Carcinoma
Cancer that begins in the skin or in tissues that line or cover internal organs
Sarcoma
Cancer that begins in bone, cartilage, fat, muscle, blood vessels or other connective or supportive tissue
Leukemia
Cancer that starts in blood-forming tissue such as the bone marrow and causes large numbers of abnormal blood cells to be produced and enter the blood
Lymphoma and Myeloma
Cancers that begin in the cells of the immune system
Central nervous system cancers
Cancers that begin in the tissues of the brain and spinal cord
Ways to treat cancer
Surgery Radiotherapy Chemotherapy
Radiotherapy
The destruction of cancer cells using radiation. Treatment is carefully directed at the site of the tumor.
Chemotherapy
Using chemicals to kill dividing cells. Treatment may be administered by drip or orally.
Centromere
Structure which joins to chromatids when the chromosomes are replicated
Chromatid
One of the two DNA threads which form part of a replicated chromosome
Genes
Sections of DNA located at specific regions on chromosomes Contain the necessary information responsible for the unique characteristics present in living organisms
Centrioles
Arranged at right angles to each other Control the formation of spindle involved in the movement of replicated chromosomes away from one another during cell division
Endoplasmic Reticulum
Increases internal surface area of cell Makes, stores and transports carbohydrates, proteins and lipids
Ribosomes
Small granules found in the cytoplasm of all cells Make new proteins
Those in cytoplasm produce proteins needed by cytoplasm
Those in ER produce proteins that form part of the membranes or are secreted
Golgi Bodies
Consist out of a stack of membranes called cisternae Membranes pinch off to form vesicles that contain proteins and lipids
Function of Golgi Bodies
Collect molecules from the ER, pack them into vesicles and distribute them to different parts of the cell where they are needed or secreted Proteins secreted from the cell can be hormones or enzymes needed in the body Form lysosomes
Vesicles and Vacuoles
Structures filled with fluid and surrounded by a membrane Control amount of water in the cytoplasm Vesicles from Golgi Bodies contain proteins and lipids
Lysosomes
Tiny sacs formed from vesicles produced by the Golgi Body Contain enzymes that can breakdown lipids, proteins and carbohydrates
Function of Lysosomes
Destroy foreign material inside or outside cell Digest and breakdown food particles Breakdown dead cells and organelles
Cell wall
Made out of cellulose Some cells have lignin in the cell walls (extra strength) Permeable to water and mineral salts Cell walls of adjacent cells joined by thin layer of lamella
Function of Cell wall
Gives cell its shape Supports and protects the cell
Plasmodesmata
Cytoplasmic channels that connect adjacent plant cells
Plant vacuoles
Surrounded by tonoplast Contains cell sap
Function of plant vacuoles
Store sugars, minerals and pigments Cell sap helps give cell its shape Plays a role in the digestion and secretion of cellular waste Osmoregulation
Turgor pressure
The pressure exerted by the swollen vacuole outwards on the cell wall
Chloroplasts
Contain chlorophyll Made up of stroma Contains the NB enzymes for photosynthesis Has a double membrane
Leucoplasts
Colorless Store starch
Thylakoids
Suspended in stroma Stacks of membrane like structures The site of photosynthesis
Chemical Equation for photosynthesis
CO2 + H2O → C6H12O6 + O2
Validity
Refers to the experimental procedures (the method used) Repeat investigation Record data over longer period Increase sample size
Reliability
Refers to the results (amount of data obtained) Control and Experimental setup Fixed variables
4 Types of animal tissue
Epithelial Connective Muscle Nervous
Sensory neurons
Send information gathered by receptors from internal and external stimuli to the brain.
located in the skin, eyes and ears
Motor neurons
Send information from the brain to the effectors (muscles and glands).
located in the spinal cord, brain and body
Interneurons
Connect sensory neurons to motor neurons
located in the brain and spinal cord
Nervous tissue
Produces and conducts electrochemical signals between organs of the body and the brain.
Connective tissue
Supports, stablizes and protects the body's many organs. Consists of cells surrounded by fluid or materials.
Dense connective tissue
Connect muscle to bones and bones to bones.
located in the tendons, around muscles and under the skin
Loose connective tissue
Supports, insulates and nourishes organs.
located between organs and under the skin
Blood
Transports oxygen, nutrients, water and other chemicals throughout the body. Helps develop immunity.
located in the circulatory system
Cartilage
Absorbs shock and friction.
located near the joints and in the ear, nose and trachea
Bone
Provides framework for body and site for muscle attachment
Skeletal muscle tissue
Striated, Multinucleated Voluntary movement Attached to bones in the skeleton
Smooth muscle tissue
Non-striated, Spindle shaped, One nucleus per fibre Involuntary movement Found in the digestive system and walls of veins and arteries
Cardiac muscle tissue
Striated, One nucleus per fibre
Involuntary movement
Responsible for heartbeat
Squamous epithelium tissue
Thin, irregular cells with large flattened nucleus Protect underlying tissue from friction and allow for movement of substances Found in the lining of the mouth, oesophagus, blood vessels and alveoli of the lungs
Columnar epithelium tissue
Elongated cells with oval nucleus, some have microvilli Support other types of cells, involved in secretion of mucus during digestion Lines the intestine
Ciliated columnar epithelium tissue
Ciliated columnar epithelium cells Cilia in lungs help trap dust particles Lines nasal cavity, trachea, bronchi, female reproductive system
Cuboidal epithelium
Square shaped cells with oval nucleus Secretory functions Lines glands
Stratified epithelium
Several layers of cells , cells in outer layers are dead Reduces friction in areas exposed to heavy friction Found on the surface of skin and inside lining of mouth
Stratified squemous epithelium
Squamous cells atop of multiple layers of cells varying from cuboidal to columnar Functions in protection
Stratified cuboidal epithelium
Two layers of cuboidal cells Functions in absorption and secretion
Stratified columnar epithelium
Single layer of columnar cells on several layers of cuboidal cells.
Functions in protection and secretion
Transitional epithelium
Cells vary depending on stretch, surface cells often large, round and bi-nucleated. Occurs only in bladder, ureter and urethra
Formation of organisms
Cells → Tissues → Organs → Organ systems → Organisms