Cells and organelles Flashcards by An Nakamura

Definition of a cell

Semi independent, living unit within body (completely independent in unicellular)
Site of metabolism mechanisms, growth, replication
Made up of aqueous solution of organism molecules, membrane bound

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Definition of an organelle

Subunit within cell
Defined structure w specific integrated activities
Not all are membrane bound

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Definition of a tissue

Organized assembly of cells and extracellular products

Carry out similar, coordinated activities in body

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Definition of an organ

Assembly of tissues, coordinated to perform specific body functions

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Definition of a system

Assembly of organs w specific, related activities, sharing regulatory influences
Can be a diffuse functional network of cells situated in many body parts, sharing specific activities

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Definition of a prokaryote

Unicellular organism, circular strand of free chromosomes

No membrane bound organelles

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Definition of a eukaryote

Uni/multicellular, chromosomes in nucleus, normally have cytoplasmic, membranous organelles, DNA divided into many linear chromosomes, vary from cel to cell within organism
Includes complex organisms

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Definition of a virus

Assemblage of DNA/RNA and proteins, parasitic of prokaryotes/eukaryotes
Invade cell, hijack protein synthesis to make more viruses
Only operate in host cells, no plasma membrane

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What are living organisms made up of

Cells

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What are higher organisms considered

Communities of vells

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What can individual cells within communities do

Peform specialized functions

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What is not considered a cell

Virus

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Genetic structure of prokaryotes

Single, circular chromosome
In nuclei
No nucleus
No histones
Has plasmids

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Genetic structure of eukaryotes

Paired chromosomes
Membrane bound nucleus
Has nucleolus
Has histones
Has extrachromosomal DNA in mitochondria and plasmids

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Intracellular structures of prokaryotes

No mitotic spindle
No sterols
Internal membrane only in photosynthetic organisms
No ER
Respiration at cell membrane
No golgi
No lysososomes
No peroxisomes
70S ribosomes
No cytoskeleton

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Intracellular structures of eukaryotes

Has mitotic spindle
Has sterols
Has membrane bound organelles
Has ER
Respiration at mitochondria
Has golgi
Has lysosomes
Has peroxisomes
80S ribosomes in cytoplasm, 70S in mitochondria
Has cytoskeleton

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Extracellular structures of prokaryotes

Peptodoglycan, LPS, teichoic acid cell wall
Has capsule/slime layer
No cilia
Has pili and flagella

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Extracellular structures of eukaryotes

Most don’t have cell walls, chitin in fungi
Most don’t have capsules or slime layers, pellicle/shell in some parasites
Cilia in some cell types
No pilli
Flagella in some cell types

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Reproduction of prokaryotes

Binary fission

Asexual

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Reproduction of eukaryotes

Mitosis/meiosis

Asexual/sexual

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What is cell theory

All living things are made from cells

Arise through division of preexisting cells

Subcellular resolution and microscopes

Only EM can reveal subcellular details
TEM, see ultrastructure, electrons go through specimen
SEM, see cell surface, electrons scattered off cell surg=face by heavy metal coating of Au

Downfalls of EM

Elaborate prep needed

Only dead cells can be viewed

What limits the max size of a cell

Diffusion<50um = efficient

As cell size increases, V:SA decreases

How do specialized cells overcome the limitations of diffusion

Thin processes Giant multinucleate cells Gap junctions

Whats a thin process

Directed transport of substances around cell via, cytoskeleton (neurons, oligodendrocytes)

Giant multinucleate celles

Gene expression occurs in more than 1 place (skeletal muscle cells)

Gap juctions

Channels between cells, allow movement of substances between cells

Purpose of membrane bound cellular organelles

Allows specialized environments within Different functions operate under different conditions (pH) Single cell can have many functional compartments

Protein filaments that make up the cytoskeleton

``` Actin -thinnest muscle fibres Microtubules -thickest, pull daughter cells apart Intermediate filaments -mechanical strength of cell ```

Function of cytoskeleton

Contribute to mechanical strength, control shape, drive, guide material movement

What is the cytosol

Aqueous environment in plasma membrane

What is the cytoplasm

Cytosol + organelles

Size of nucleus

Largest organelle | 3-10um

Function of nucleus

Contains packaged genetic material DNA organized as chromosomes Chromatin= complex of DNA/histone and non histone proteins which form nucleosome When cell not dividing, uncondensed chromatin

Function of nucleolus

Site of rDNA transcription, assembly site of ribosomes

How many membranes does the nuclear envelope have

Double membrane

Function of nuclear pores

Allows transport in and out of nucleus

Function of SER

Biosynthesis of membrane lipids, steroids | Start of N linked glycosylation, detoxification of xenobiotics

Function of RER

Covered in ribosomes, translation, proteins for secretion/insertion into cell membrane Proteins folded, disulphide bridges Vesicles bud from RER, sent to golgi

Structure of golgi body

4-8 stacks of cisterna, membrane bound channels Modifies proteins from RER via vesicles Modifies N linked carbohydrates Glycosylation of O linked carbohydrates and lipids Synthesis and package secretory materials Direct new proteins in vesicles to compartments Transport membrane lipids around cell Create lysosomes

Structure of secretory vesicles

Bud off form golgi

Function of secretory vesicles

Fuse with inner surface of plasma membrane, exocytosis of hormone, neurotransmitters

Function of peroxisomes

``` Detoxification Oxidation of VLCFA Contains oxidative enzymes, form H2O2 Contains enzymes that neutralize H2O2, form H2O and O2 Site of phospholipid synthesis ```

Structure of lysosomes

>50 types of hydrolytic enzymes for all major macromolecules, low pH needed for acid hydrolysis Involved in organelle turnover/autophagy Uses ATP to pump H+ into lysosome

Size of mitochondrion

0.5-2um

How to synthesis mitochondrial proteins

Have mitochondrial DNA

Function of mitochondria

Oxides sugars and generate ATP in Krebs

Structure of mitochondrion

Have double membrane Cristae increase SA:V Krebs cycle enzymes/ETC in different parts of the membrane structure

Size of a lysosome

0.2-0.5um

Size of peroxisome

0.2-0.5um