7.2. Cell divided into: Cytoplasm (found outside the nucleus) Nucleus.
Cell Structure and Function€¦ · cytoplasm in the nucleus. The Nucleus This is an electron...
Transcript of Cell Structure and Function€¦ · cytoplasm in the nucleus. The Nucleus This is an electron...
Cell Structure and Function
Biology 12Unit 1 – Cell Structure and Function
Inquiry into Life pages 45 – 59 and 68-69
Assignments for this Unit
● Pick up the notes/worksheet for this unit and the project
● There will be test at the end of the unit composed of 3 parts:– Matching keyterms
– Multiple Choice
– Labelling Diagrams
Cell Structure
Cell Theory
Cells are the functional unit of life
They comprise the smallest living unit of any organism
All cells come from pre-existing cells
Cells have a complex structure and many specialized organelles
These organelles often work inter-relatedly
The Nucleus
can be observed as the large, centrally located control centre of the cell
surrounded by a double layered membrane with pores
contains DNA – deoxyribonucleic acid
transcription and replication of DNA occurs here
The Nucleus
Nuclear Membrane
The Nucleus
The nuclear membrane (nuclear envelope) is what separates the nuclear material from the rest of the cytoplasm
It consists of a double membrane with pores
The Nucleus
Nuclear Membrane
Nuclear Pore
The Nucleus
Nuclear pores are channels that allow the passage of protein molecules into the nucleus and ribosomal subunits out of the nucleus
The pores are ~ 100 nm in diameter, or about 1/10 000 000 metres
The Nucleus
Nuclear Membrane
Nuclear Pore
Nucleolus
The Nucleus
The nucleolus is the most prominent structure in the nucleus, seen as a dark, spherical mass
The nucleolus produces ribosomal RNA (ribonucleic acid) = rRNA
rRNA joins with proteins to form the subunits of ribosomes
The Nucleus
Nuclear Membrane
Nuclear Pore
Nucleolus
Chromatin
The Nucleus
Chromatin is DNA and associated proteins in their uncoiled state
During interphase, chromosomes are unwound and and cannot be distinguished individually
The chromatin is immersed in a semifluid medium called nucleoplasm, which is like cytoplasm in the nucleus
The Nucleus
This is an electron micrograph of a liver cell nucleus
Notice:
nuclear membranenuclear membrane
nucleolusnucleolus
chromatinchromatin
nucleoplasmnucleoplasm
nuclear pores?nuclear pores?
Ribosomes
Ribosomes are small granules that appear dark in micrographs
They are involved in protein synthesis – forming chains of amino acids to make long protein molecules
Found on the endoplasmic reticulum and free floating in the cytoplasm
Ribosomes
Cytoplasmic ribosomes are often found in small clusters called polyribosomes or polysomes
These produce proteins that are used inside the cell
Ribosomes
Most ribosomes are found attached to the surface of the endoplasmic reticulum (ER)
These produce proteins to be transported outside the cell through the ER
Endoplasmic Reticulum
A series of membranous channels and flattened vesicles that are physically connected to the nuclear membrane
The ER works with other organelles to restrict chemical reactions to particular areas
Endoplasmic Reticulum
Rough endoplasmic reticulum (rough ER) is superficially covered in ribosomes
These ribosomes synthesize proteins that enter the ER
Endoplasmic Reticulum
Endoplasmic Reticulum
Glycoproteins can be found on the extracellular side of the cell membrane
Proteins in the ER undergo modification, often forming a glycoprotein (protein with an attached carbohydrate molecule)
Endoplasmic Reticulum
The proteins are then transported to the Golgi apparatus after processing
Endoplasmic Reticulum
Smooth ER is a different form where there are no ribosomes on the surface
Smooth ER is continuous with rough ER
Different functions depend on the type of cell they are in
synthesize phospholipids that are on the synthesize phospholipids that are on the surface of the cell membranesurface of the cell membrane
testosterone production in testestestosterone production in testes
detoxifying in the liverdetoxifying in the liver
Endoplasmic Reticulum
Smooth ER always forms vesicles to transport proteins to the Golgi apparatus
Vesicles
Vesicles are membranous sacs used to transport compounds around the cell
often formed from the Golgi apparatus or from the infolding of the cell membrane
Vesicles
Golgi Apparatus
Also known as Golgi bodies
Appear as a series of flattened pancakes (saccules)
Golgi Apparatus
Functions to process, package, and secrete
Further processes proteins
These proteins are packaged into vesicles
The vesicles are are formed from the Golgi apparatus membrane where they will secrete their contents from the cell membrane --> exocytosis
Vesicle Secretion
Lysosomes
Lysosomes are membrane-bound vesicles of digestive enzymes produced by the Golgi appartus
Essentially “suicide sacs”
Functions:
attach to food vacuoles to digest contentsattach to food vacuoles to digest contents
destroys old or malfunctioning organelles destroys old or malfunctioning organelles
Lysosome
Vesicle Budding and Secretion
http://www.sumanasinc.com/webcontent/animations/content/vesiclebudding.html
Mitochondria
Singular is mitochondrion
Site of cellular respiration
glucose + oxygen --> carbon dioxide + water glucose + oxygen --> carbon dioxide + water + ATP (energy)+ ATP (energy)
CC66HH
1212OO
66 + 6 O + 6 O
22 --> 6 CO --> 6 CO
22 + 6 H + 6 H
22O + ATP (energy)O + ATP (energy)
Cells use ATP (adensine triphosphate) for energy
The more active the cell, the more energy it requires, the more mitochondria they have
eg. muscle cells
Mitochondria
Mitochondria
Bound by a double membrane
Inner membrane invaginates (folds in) forming cristae, creating a high surface area for chemical reactions
Inner filled spaced called the matrix, containing its own DNA, ribosomes, enzymes
Chloroplasts
Chloroplasts are the site of glucose production in autotrophs through a process called photosynthesis
They convert solar energy into chemical energy
carbon dioxide + water -----> glucose + oxygen
6 CO2 + 6 H
2O -----> C
6H
12O
6 + 6 O
2
solar energy
solar energy
Chloroplasts
Chloroplasts have a double membrane
The inner fluid-filled space is called the stroma
Within the stroma are interconnected sacs called thylakoids
Thylakoids can be stacked to form grana (sing. granum)
Chloroplasts
Chloroplasts
Chlorophyll is a green pigment found within the thylakoid membranes in grana
Photosynthesis takes place specifically within the grana in chloroplasts
Also in the stroma is DNA, ribosomes, and enzymes, just like in the matrix of mitochondria!
Vacuoles
Membrane bound sac filled with water and/or chemicals
Used in animal cells for the digestion of food and the elimination of excess water through exocytosis
Used in plant cells for storage of metabolic wastes and “pressurizing” the cell
Cell Organelles Video
http://www.teachersdomain.org/resource/tdc02.sci.life.cell.organelles/
Cell Membrane
Also known as the plasma membrane
Separates the internal environment (intracellular) with the external environment (extracellular)
Composed of a phospholipid bilayer with various partially and wholly embedded proteins
Cell Membrane
Cell Membrane
The description of the membrane is called the Fluid Mosaic Model
It has a fluid consistency, like vegetable oil
Proteins are scattered within the membrane and on the intracellular surface
Cell Membrane
Cell Membrane
The phospholipid molecule is polar – two different parts
The phosphate “head” is hydrophilic (water loving)
The lipid “tail” is hydrophobic (water fearing)
Cell Membrane
Embedded within the lipid tails are cholesterol molecules which adds strength and stiffness to the membrane
Integral proteins are those that are embedded in the phospholipid bilayer
Peripheral proteins are those that occur on one side of the bilayer or the other
Glycoproteins are only on the extracellular side of the membrane
Cytoplasm
The semifluid medium between the cell membrane and the nucleus that contains organelles
Cell Membrane, Nucleus and Cytoplasm Video
http://www.teachersdomain.org/resource/tdc02.sci.life.cell.nucleus/
Cell Wall
Found only in plant cells – two types
It is a permeable, rigid structure that adds support and protection
Primary cell walls are composed of cellulose molecules
Secondary cell walls are composed of lignin, an even stronger molecule
Cell Wall (primary)
copyright © Dennis Kunkel. All rights reserved.
Cell Wall (primary)
Cytoskeleton
Composed of a network of interconnected filaments and tubules
Maintains cell shape and structure, causes cells and organelles to move
Can be assembled and disassembled very rapidly
Three components:
actin filamentsactin filaments
microtubulesmicrotubules
intermediate filamentsintermediate filaments
Cytoskeleton
Cytoskeleton
Cytoskeleton
actin filaments
intermediate filaments
microtubules
Cytoskeleton Tutorial
http://www.wiley.com/college/pratt/0471393878/student/animations/actin_myosin/index.html
Flagella and Cilia
Flagella and cilia are structures composed of microtubules and are used for locomotion
http://programs.northlandcollege.edu/biology/Biology1111/animations/flagellum.html
Summary
Organelles are membrane bound structures with varied and dedicated functions
Some organelles work together, forming a network to move materials throughout the cell
rough ER and smooth ERrough ER and smooth ER
Golgi apparatusGolgi apparatus
vesiclesvesicles
cell membranecell membrane
Summary
Mitochondria and chloroplasts are double-membrane bound energy-related organelles
Photosynthesis occurs in the grana of chloroplasts
Cellular respiration occurs in the matrix of mitochondria
Probable independent origin due to the presence of extranuclear DNA
Summary
All cells maintain their structure using a dynamic cytoskeleton composed of three types of elements
Plant cells have additional means of support – a permeable cell wall and a large central vacuole that maintains turgidity