Cells and tissues Anas Power point Flashcards
Cell theory
basic structural and functional unit of living organisms collective activness of cells subcellular structures – function of cells Cells arise from pre-existing cells
Chemical Components of Cells
Carbon Hydrogen Oxygen Nitrogen
Anatomy of the Cell
three main regions Nucleus Cytoplasm Plasma membrane
The Nucleus
Control center of the cell Contains genetic material (DNA) Three regions Nuclear envelope (membrane) Nucleolus Chromatin
The Plasma Membrane
Double phospholipid layer Hydrophilic heads Hydrophobic tails Also contains proteins, cholesterol, and glycoproteins
Membrane junctions
Tight junctions (impermeable) Bind cells together into leakproof sheets Desmosomes Anchoring junctions Gap junctions Allow communication
Cytoplasm
Site of most cellular activities Major elements: Cytosol Fluid that suspends other elements Organelles Metabolic machinery of the cell Inclusions Chemical substances (stored nutrients, cell products,etc.)
Cytoplasmic Organelles
Mitochondria
Carry out reactions where oxygen is used to break down food
Provides ATP for cellular energy
Ribosomes
Protein + ribosomal RNA
Sites of protein synthesis
a)Part of the rough endoplasmic
reticulum
a)Free in the cytoplasm
Transport how this process works
1 As the protein is synthesized on the
ribosome, it migrates into the rough ER
cistern.
2 In the cistern, the protein folds into its
functional shape. Short sugar chains
may be attached to the protein (forming
a glycoprotein).
3 The protein is packaged in a tiny
membranous sac called a transport
vesicle.
4 The transport vesicle buds from the
rough ER and travels to the Golgi
apparatus for further processing.
Cytoplasmic Organelles
Modifies and packages proteins as:
Cell membrane components
Secretory vesicles
Lysosomes
Cytoplasmic Organelles
Lysosomes
Contain enzymes produced by ribosomes
Packaged by the Golgi apparatus
Digest worn-out or nonusable materials within the cell
Cytoplasmic Organelles
Peroxisomes
Membranous sacs of oxidase enzymes
Detoxify harmful substances
Break down free radicals
Replicate by pinching in half
Cytoplasmic Organelles
Cytoskeleton
internal protein framework of the cell
Three different types of elements
Microfilaments (largest)
Intermediate filaments
Microtubules (smallest)
Cytoplasmic Organelles
Centrioles
Rod-shaped bodies made of microtubules
Direct the formation of mitotic spindle during cell division
Cellular Projections
Cilia move materials across the cell surface (respiratory system)
Flagella - propel the cell (sperm)
Microvilli - Increase surface area for absorption
Cell diversity
Cell’s shape reflects its function
Cells that connect body parts
Fibroblast, erythrocyte
Cell that covers and lines body organs
Epithelial cell
Cells that move organs and body parts
Muscle cells
Cell that stores nutrients
Fat cell
Cell that fight disease
Macrophage
Cell that gathers information and control cells
Nerve cell
Cell diversity
. Cells of reproduction
Oocyte
Sperm
Solutions and Transport
Solution—homogeneous mixture of two or more components
Solvent—dissolving medium;
Solutes—components in smaller quantities within a solution
Intracellular fluid —nucleoplasm and cytosol
Interstitial fluid —fluid on the exterior of the cell
Selective permeability – barrier (plasma membrane) selects substances to pass through it
MEMBRANE TRANSPORT
PASSIVE
No energy is required
DIFFUSION
FILTRATION
ACTIVE Cell provides the metabolic energy (ATP)
Passive Processes
Diffusion
Movement is from high concentration to low concentration, or down a concentration gradient
Types of diffusion
Types of diffusion
Simple diffusion
lipid-soluble or small molecules
through membrane pores
Facilitated diffusion
lipid-insoluble and large
substances that require
a protein carrier or a channel
Osmosis
Diffusion of water through
aquaporins
•Filtration
Water and solutes are forced through a membrane by fluid, or hydrostatic pressure
Active Processes
Substances unabled to pass by diffusion
ATP is used for transport
ACTIVE TRANSPORT
ATP energizes protein carriers
substances are moved against concentration gradients
VESICULAR TRANSPORT
Exocytosis
Endocytosis
Phagocytosis – “cell eating”
Pinocytosis – “cell drinking
Cell Life Cycle
Cells have two major periods
Interphase
Cell grows
metabolic phase
Cell division
Cell replicates itself
DNA Replication
Always precedes cell division
Genetic material is duplicated
DNA uncoils and each side serves
as a template
Events of Cell Division
Mitosis—division of the nucleus
Results in the formation of two daughter nuclei
Cytokinesis—division of the cytoplasm
Begins when mitosis is near completion
Results in the formation of two daughter cells
http://www.ck12.org/life-science/Cell-Cycle-in-Life-Science/lecture/Cell-Division-and-the-Cell-Cycle/
Stages of Mitosis
Interphase
Cell performs normal functions, Cell growth (G1 and g2), Synthesizes new molecules and organelles
Prophase
Changes occur in nucleus and cytoplasm, chromatin fibers become more tightly coiled and folded, Nucleoli disappear, each duplicated chromosome appears as two identical sister chromatids, mitotic spindle begins to form.
Prometaphase
Nuclear envelope disappears,, each sister chromatid has a protein structure called the kinetochore, some microtubules attach to kinetochores
Metaphase
Mitotic Spindle is fully formed, poles at opposite end of cell, chromosomes convene on metaphase plate, centrometres are lined up on the metaphase plate, for each chromosome the kinetochores of sister chromatids face opposite poles.
Anaphase
Two centrometres of each chromosome come apart separating sister chromatids, each sister chromatid (once separated) becomes a full fledged daughter chromosome. Daughter chromosomes are walked to opposite poles of cell.
Telophase
“Reverse of Prophase”, cell elongation (anaphase) continues, chromatin fiber of each chromosome uncoils and nucleoli reappear, at the end of this phase the mitotic spindle reappears
Cytokinesis
The final stage of the cell cycle, in which the cell’s cytoplasm divides, distributing the organelles into each of the two new cells. Involves a cleavage furrow which pinches the cell in two.
Protein Synthesis
- Gene—DNA segment that carries a blueprint for building one protein
- Proteins have many functions
▫Building materials for cells
▫Act as enzymes (biological catalysts)
•RNA is essential for protein synthesis
Role of RNA
Messenger RNA (mRNA)
Carries the instructions for building a protein from the nucleus to the ribosome
Transfer RNA (tRNA)
Transfers appropriate amino acids to the ribosome for building the protein
Ribosomal RNA (rRNA)
Helps form the ribosomes where proteins are built
Transcription and Translation
Transcription – in the nucleus
Transfer of information from DNA to mRNA
Three-base sequences on mRNA are called codons
Translation – in the cytoplasm
Base sequence of nucleic acid is translated to an amino acid sequence - building blocks of proteins
Body Tissues
