the cell student copy 2012

8/13/2019 The Cell Student Copy 2012

1/29

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


2/29

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


3/29

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


4/29

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


5/29

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


6/29

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


7/29

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


8/29

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


9/29

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?


10/29


11/29

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


12/29

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


13/29

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!)


14/29


15/29

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:-


16/29

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


17/29

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


18/29

Intra/extracellular ion distribution

K + NA + NA +

K +

Cl-

Cl-

Ca 2+

-

-

-

--

-

- --

-

-

-

Cl-

10 times more Sodium outside cell than inside20 times more potassium inside cell than outsideAlso more calcium and chloride outside cell

FIXED ANIONS


19/29

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


20/29

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


21/29


22/29

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


23/29

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


24/29

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


25/29

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


26/29

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.


27/29

Nervous Tissue

Contains nerve cells or neuronswhich are sensitive to stimuliand respond with impulsesAlso, the tissue containssupporting cells called neurogliawhich support the neurons.


28/29

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


29/29

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

the cell student copy 2012

Documents