Cells and tissues Anas Power point Flashcards by Lin Craddock

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

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Chemical Components of Cells

Carbon Hydrogen Oxygen Nitrogen

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Anatomy of the Cell

three main regions Nucleus Cytoplasm Plasma membrane

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The Nucleus

Control center of the cell Contains genetic material (DNA) Three regions Nuclear envelope (membrane) Nucleolus Chromatin

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The Plasma Membrane

Double phospholipid layer Hydrophilic heads Hydrophobic tails Also contains proteins, cholesterol, and glycoproteins

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Membrane junctions

Tight junctions (impermeable) Bind cells together into leakproof sheets Desmosomes Anchoring junctions Gap junctions Allow communication

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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.)

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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

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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.

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Cytoplasmic Organelles

Modifies and packages proteins as:

Cell membrane components

Secretory vesicles

Lysosomes

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Cytoplasmic Organelles

Lysosomes

Contain enzymes produced by ribosomes

Packaged by the Golgi apparatus

Digest worn-out or nonusable materials within the cell

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Cytoplasmic Organelles

Peroxisomes

Membranous sacs of oxidase enzymes

Detoxify harmful substances

Break down free radicals

Replicate by pinching in half

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Cytoplasmic Organelles

Cytoskeleton

internal protein framework of the cell

Three different types of elements

Microfilaments (largest)

Intermediate filaments

Microtubules (smallest)

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Cytoplasmic Organelles

Centrioles

Rod-shaped bodies made of microtubules

Direct the formation of mitotic spindle during cell division

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Cellular Projections

Cilia move materials across the cell surface (respiratory system)

Flagella - propel the cell (sperm)

Microvilli - Increase surface area for absorption

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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

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