the cell student copy 2012
TRANSCRIPT
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THE CELLLearning Outcomes
1. Describe the role of the cell in the human body2. Outline the structure and functions of the plasma membrane
and internal organelles, including the nucleus.3. List four mechanisms for cell membrane transport with
examples4. Identify four basic types of body tissue, describe their
structure and functions and provide examples of theirlocation.
5. Identify the 3 different types of muscle tissue and their principal locations.6. Define an organ and identify the principal organs that
comprise each system of the body7. Identify the principal body systems and state their main
functions
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Cells
Refer to Learning Outcome 1. Are the structural units of all living matterOur body is made up of many millions of
cells, about 200 different typesCells range in size from about 2 micrometres (tiny!)
Cells make up tissues
Tissues make up organs Organs make up systems
So. Alteration in cellular functioning or activity leads toalterations in how systems work . Diseases
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Cells (continued) Cells are the smallest biological unit capable of an
independent existence
Cells have differing shapes, sizes and functions
But.
All cells originate from that one fertilised egg cell -ZYGOTE
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3 major areas:Nucleus, cytoplasm, and plasma membrane
1. Nucleus: The control center, it directs cell activity and isnecessary for reproduction. Contains our genetic material(DNA)
2. Plasma membrane: Acts as a barrier and allows selectivemovement of substances in and out of the cell
3. The cytoplasm: Made up of a gel like fluid cytosol andspecialised bodies called organelles
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The Cell Label the diagram with thefollowing structures:
1. Nucleus2. Rough ER (with
ribosomes)3. Ribosomes4. Smooth ER5. Golgi apparatus /
complex6. Secretory granules7. Nuclear envelope/
membrane8. Mitochondria
9. Plasma membrane10. Centrosome11. Centrioles
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Simplified cell membrane structure
P
r o t e i n
As lipids are hydrophobic /non polar they restrict the passage of H 20 andions through therefore it acts as a barrier
Hydrophobic end
Hydrophilic end
Based on a lipid bilayer (phospholipids) and proteinsMembrane is fluid- not solid so lipids and proteins can move freely
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Proteins have 3main functionsin the cellmembrane asillustrated on the
right and left
Membrane proteins are either peripheral (partially in oneside) or integral (spans one side to another)
Proteins provide a specialised function in selectivetransport , structural support, transport, enzyme or receptors
The role of proteins in the cell membrane
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Cell receptors and intracellularsignalling
Communication between cellsdepends on receptors located onthe exterior part of the cellmembrane
Act as docking sites forchemical molecules e.g.hormones, neurotransmitters &drugs
Result: Lead to a series ofresults that result in either turnon and turn off target cellactivity
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Plasma Membrane Refer to Learning Outcome 2
Keeps the cell intact enclosing the cell contents
Controls movement in and out of the cell
Semi permeable it allows somesubstances to pass through and others not
Acts as a receptor site and helps othercells recognise it (proteins)
Why is the barrier so important?
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Nucleus
The CONTROL CENTRE for the cell
Contains CHROMOSOMES which carry all our geneticinformation as GENES (sections of DNA)
This genetic material is the recipe that instructs or governswhat the cell does/is
This information is replicated during cell division so thatall daughter cells have the same genetic information and
instructions as parent cell (non sex cell division)Gives instructions to the rest of the cell for protein
synthesis (via the organelles)
Nuclear membrane is semi-permeable double membrane
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OrganellesMitochondria power centre of the cell where energy in
the form of Adenosine Triphosphate is made (ATP)
Endoplasmic Reticulum extensive network of membranoustubules from nuclear membrane to cell membrane.
1. Passageway for transport of the materials needed for cellfunction within the cell
2. Synthesise lipids and carbohydrates, contain enzymes
*Rough Endoplasmic Reticulum- with ribosomes
Smooth ER without ribosomes
Ribosomes- site of protein synthesis, either in ER or free incytoplasm
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Organelles
Golgi Apparatus flattened membranous
sacs which package up and modify proteins sent by RER. Secretoryvesicles pinch off from ends of sacs totransport proteins to plasma membraneeg. Mucus, digestive enzymes.
Centrosome (contains centrioles) Formsthe mitotic spindle during cell division
Lysosomes contains digestive enzymeswhich breakdown unwanted substances(trash bin!)
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Cell TransportLearning Outcome 3
Essential for cell nutrition, excretion of waste, and cellrespiration
Can be either: ACTIVE the cell uses energy to do this PASSIVE there is no energy expenditure
from the cell
FOUR mechanisms for transport:-
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Transport MechanismsDiffusion: Molecules scatter evenly throughout an area
and mover from a high to low concentration,eg O 2 moves from capillaries into cell
Bulk Transport: Large particles transported across the cellmembrane by:
Exocytosis - out
Endocytosis - in Phagocytosis - eating
Osmosis: Diffusion of a solvent through a semi-permeablemembrane * Passive tr ansport
* Active transport energy is used
* Passive tr ansport
Facilitated Diffusion when a substance uses a carrier
molecule to help it across the membrane eg. Glucose
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Transport mechanisms
Facilitated diffusion: Involvestransport of substance throughcell membrane by means ofmembrane carrier. Moves fromhigh to low conc
Active transport: Movement of molecules andions against their concentration gradients . Fromlower to higher concentrations. Requires energy
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Intra/extracellular ion distribution
K + NA + NA +
K +
Cl-
Cl-
Ca 2+
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Cl-
10 times more Sodium outside cell than inside20 times more potassium inside cell than outsideAlso more calcium and chloride outside cell
FIXED ANIONS
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Cell Respiration
All cells need energy for activity or metabolism,including breathing!
Chemical energy is used this is called ATP
ATP - Synthesised from Glucose and Oxygen in the cell smitachondria (gluocose + oxygen CO 2 + H 2O + ATP)
Called aerobic respiration
When no O 2 available, Glucose is converted to LacticAcid to make ATP called ANEROBIC respiration
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Cell Division
Essential for body growth and tissue repair
Process called MITOSIS
Nerve tissue, skeletal muscle and heart musclelose there ability to divide when mature
Mitosis produces 2 identical daughter cells
Each new cell has 23 pairs of Chromosomes
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Meiosis Is a specialised division of the sex cells these
are the ovum and sperm.
This type of division gives rise to non -identical
cells which have half the number of chromosomes(23).
Often called reduction division .
Will be considered in the Principles ofInhertiance
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4 Basic Tissue Types Epithelial Tissue
covers body surfaces; lines body cavities, hollow organsand ducts (tubes) and forms glands
Muscular Tissue
generates the physical force needed to make the body move Nervous Tissue
detects changes inside and outside the body and initiates and transmits nerve impulses that coordinate body
activities to help maintain homeostasis Connective Tissue
protects and supports the body and its organs, binds organstogether, stores energy reserves as fat and providesimmunity
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EpitheliumContinuous sheets of cells in either single or multiple layers
Simple squamous epith eg.Lining of vessels, heart, airsacs (filtration, diffusion,secretion and osmosis)
Simple cuboidalepith, eg, ovary,kidney tubules,ducts of glands(secretion &absorption)
Blood supply is from surrounding connective tissueCovering/lining, glandular, stratified, ciliated look at thesetypes in your book
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Others include; Compact Bone (support/protection/,contains blood forming tissue, movement) Blood
(transport of nutrients and oxygen, immune responses) ,Elastic Cartilage (support/shape eg. Ear lobe, epiglottis)
Hyaline Cartilage
(smooth surface for joint movment ends of bone, nose,fetal skeleton)
Elastic CT, AerolarCT (in dermis strength/support)
CONNECTIVE TISSUE
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Muscle Tissue3 distinct type; Smooth muscle in walls of hollow internal structures
such as blood vessels, airways to lungs, stomach etc.Fibres are thicker in middle and taper at each end. Also
called involuntary. Skeletal muscle attached to bones of skeleton and is
striated (has light and dark sections). Also calledvoluntary muscle fibres
Cardiac muscle looks like skeletal and is striated BUTit is involuntary as not controlled by conscious control ,Are branched fibres with one centrally located nucleus.
Look at difference in structure of these 3 different types of muscle tissueand state which 2 are similar in structure.
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Nervous Tissue
Contains nerve cells or neuronswhich are sensitive to stimuliand respond with impulsesAlso, the tissue containssupporting cells called neurogliawhich support the neurons.
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Most organs represent all 4 tissue types. The arrangement of the tissuesdetermines the organ s structure and functional capabilities
Definition: A structur e composed of two or more ti ssue types,
that performs a specif ic function for the body
ORGANS
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BODY SYSTEMS
1. Make a list of the major body systems(male and female reproduction counts
as 2)2. State the main function for each of the
systems3. State the main organs included in each
of the systems