Cell Organelles Flashcards
What are cells?
Small units bound by a plasma membrane
Cells contain an aqueous fluid called
the cytosol
Cells contain chemicals in the
cytoplasm
Cells have structural support called the
cytoskeleton
All cells are surrounded by a
plasma membrane
The plasma membrane is a
single membrane
The plasma membrane is
selectively permeable
What is the difference between the intracellular and extracellular fluid?
The intracellular fluid is found inside the cell and the extracellular fluid is found outside the cell
What is the cytosol?
The aqueous component of the cytoplasm of a cell within which various organelles and particles are suspended
The plasma membrane is a complex of…
lipids
proteins
carbohydrates
List four carbohydrates which make up the plasma membrane
glycolipids
glycoproteins
peptidoglycans
glycosaminoglycans
Why is the plasma membrane selectively permeable?
because lipids are amphipathic
What does amphipathic mean?
A molecule especially a protein which has both a hydrophilic and hydrophobic part
What model is used to describe the plasma membrane?
The fluid mosaic model
What allows hydrophilic solutes to be transported across the plasma membrane?
Integral and peripheral membrane proteins
What are peripheral membrane proteins?
Peripheral membrane proteins stay on the perimeter of other membrane proteins
What are integral proteins?
Proteins integrated into the membrane
What are transmembrane proteins?
Proteins that transfer across the entire membrane
What is a cell wall?
Surrounds the plasma membrane - limits passage of molecules into / out of the cell
What are plant cell walls composed of?
Cellulose
What is cellulose made of?
Complex carbohydrates which have to be digested by cellulase - animals don’t have this
What are bacteria cell walls composed of?
Peptidoglycan
Bacterial cell walls can be surrounded by a
gelatinous polysaccharide layer - glycocalyx as either capsule or slime layer
Bacterial cell walls can be stained to distinguish between gram pos and gram neg by which staining method?
Gram stain
What is the difference in layers to gram pos and gram neg bacteria?
Gram positive bacteria have a single layer in the cell wall, gram negative bacteria have several layers to the cell wall
What are the cell surface appendages and where do they attach?
Attach to the plasma mem/cell wall
- villi
- cilia
- flagella
Which cell surface appendages help move the cell?
Flagella or cilia
Which cell surface appendage help move extracellular fluid
Cilia
Which cell surface appendages aid in increasing the cell’s surface area?
Villi/microvilli
What is the function of the nucleus?
Contains the cells blueprint for proteins -the DNA
What is the theory of biogenesis?
The hypothesis that all living matter arises only from other living matter
What is cell proliferation?
An increase in cell number as a result of cell division and growth
What are chromosomes?
condensed chromatin
What is chromatin?
The DNA and histone proteins
Where is the DNA, histone proteins and chromosomes contained?
In the nucleolus
What must happen in the first phase of mitosis?
Replication of the DNA blueprint
In a non-dividing cell, the DNA in the nucleus is used as a blueprint for what process?
protein synthesis
Protein synthesis is a two step process, what is the first step and where does this occur?
In the nucleus
Transcription of DNA to RNA
What is the second step in protein synthesis and where does this occur?
Translation of RNA to protein
in the endoplasmic reticulum
How are the nucleus and nucleolus separated from the cytoplasm?
By a double membrane (nuclear envelope) around the nucleus with nuclear pores
What are centrioles?
A perpendicular pair of specialist microtubules only found adjacent to the nucleus in animal cells
What are microtubules made out of?
tubulin
What is the function of centrioles?
to organise mitotic or meiotic spindle
What surrounds the mitochondrion?
a double membrne
What are the inner and outer membranes of the mitochondria separated by?
An aqueous intermembrane space
The inner membrane of the mitochondria is convoluted into cristae, why?
Increase its total surface area
Inside the inner membrane on a mitochondria is the…
Matrix
Why do mitochondria have their own DNA?
originated from an endosymbiotic process involving a bacterial cell
Mitochondria contain a series of what type of enzymes?
Oxidative enzymes
The mitochondria catalyses aerobic _______ of fuels
catabolism
The mitochondria harnesses energy as?
ATP
Glycolysis occurs in the
cytoplasm of the cell
Where does the krebs cycle occur?
in the mitochondrial matrix
Where does phosphorylation of ADP to ATP occur in the mitochondria?
inner mitochondrial membrane
The equation that harnesses energy as atp is…
c6h12o6 + 6o2 –> 6co2 + 6h20 + atp
How do mitochondria harness energy from carbon based fuels?
by oxidative phosphorylation
Which organelle generates and metabolises reactive oxygen species and free radicals?
The mitochondrion
The mitochondrion has the ability to mediate
apoptosis
what is apoptosis?
programmed cell death
What are the synthetic organelles?
chloroplasts, ribosomes, endoplasmic reticulum and the golgi apparatus
Where are chloroplasts found?
Only in photosynthetic cells
What do chloroplasts catalyse?
anabolic metabolism
What is the equation of chloroplasts harnessing light energy in photosynthesis?
energy + 6co2 + 6h20 –> c6h12o6 + 6o2
The chloroplast is bounded by a double membrane and has its own
dna
The mRNA code is translated into an amino acid sequence and then a peptide/protein by
ribosomes
What are the three types of ribosomes?
messenger rna
ribosomal rna
transfer rna
In the nucleolus, dna is transcribed into
rna
ribosomes have two subunits, one which is
large and one which is small
Each complex making up the two subunits in a ribosome is made up of
rRNA and proteins
Which component of the ribosomal rna is enzymatic?
the enzymatic component is rRNA
describe the prokaryotic ribosome
small subunit - 30S,
large subunit - 50S
70S
describe the eukaryotic ribosome
small subunit 40s
large subunit - 60s
80s
how can the different ribosomes in prokaryotes and eukaryotes be exploited?
in antibiotics
what are polysomes?
several ribosomes translating the same mRNA template
What is the endoplasmic reticulum?
A continuous, highly convoluted membrane system that spans from the nucleus to the plasma membrane
what is the difference between the rough er and the smooth er?
the rough er is embedded with ribosomes
The smooth er is the site of
lipid synthesis
the rough er is the site of
protein synthesis (translation)
Protein synthesis generally occurs in the ____ of the ____ of the rough endoplasmic reticulum
in the lumen of the cisternae
How would one describe the structure of the golgi apparatus?
a series of specialised, stacked cisternae, through which proteins (and lipids) are processed before insertion into plasma membrane and secretion from plasma membrane
Molecules enter the golgi apparatus from the
cis face
molecules exit the golgi apparatus from the
trans face
The molecules move through the golgi apparatus by
vesicular trafficking
What is vesicular trafficking?
Membrane vesicle trafficking involves movement of important biochemical signal molecules from synthesis and packaging locations in golgi body to specific release locations on the inside of the plasma membrane of the secretory cell
What are the three steps of vesicular trafficking?
- vesicle buds off from one membrane (cisterna)
- vesicle passes through the cytoplasm and fuses with another membrane
- traffics lumenal and membrane content of vesicle
What is a vesicle?
a small spherical sealed, single membrane lipid bilayer - contains intracellular fluid
The enzymes in the golgi apparatus can add carbohydrate, give two examples of this
carb + lipid = glycolipid
carb + protein = glycoprotein
What is the overall function of the golgi apparatus?
‘sorts molecules for final destination’
almost everything that goes into it comes back out but in a modified, packaged form, often ready for export from the cell
List the three digestive organelles.
endosomes
lysosomes
peroxisomes
What is an endosome?
an incoming vesicle formed by endocytosis
Endosomes bud off from plasma membranes in which two processes?
Pinocytosis and Phagocytosis
There are three types of endosomes, what are they called?
Early, recycling and late
What do late endosomes fuse with?
Vesicles containing lysozyme
What is a lysosome?
an organelle in the cytoplasm of eukaryotic cells containing degradative enzymes enclosed in a membrane.
What is a peroxisome?
Small membrane enclosed organelles that contain enzymes involved in a variety of metabolic reactions
What two types of enzymes to peroxisomes contain?
Peroxidase and catalase enzymes
Peroxisomes are involved in the initial catabolism of which four substances
long chain fatty acids, branched chain fatty acids, amino acids and polyamines
Difference between a prokaryote and a eukaryote?
Prokaryotes don’t have a nucleus and eukaryotes do have a nucleus
What is the only common organelle in prokaryotes and eukaryotes?
The ribosome
What is the nuceloid in a prokaryote?
A bacterial chromosome: single circular molecule of naked DNA , no histones
Where does the metabolism occur in prokaryotes and why?
Occurs in the cytosol because there is no ER or mitochondria
Are prokaryotes simple and eukaryotes complex?
No, there are 5 kingdoms of eukaryotes and 2 kingdoms of prokaryotes but each with multiple phyla
What are the eukaryote kingdoms?
Multicellular - animals, plants, fungi. Unicellular - yeast, amoeba
What are the prokaryotic kingdoms?
Bacteria and Archaea
How many phyla are there of bacteria
12
How many phyla are there of archaea?
6
What are the four morphologies of prokaryotes?
Cocci, bacillus, spirochetes and vibrio (curved rods/commas)
Why is it untrue to say that prokaryotes are unicellular and eukaryotes are multicellular
Some prokaryotes can be multicellular at specific stages of their life cycle and some eukaryotes are unicellular
Are archaea always unicellular?
Yes babes
Bacteria are usually unicellular but some bacteria have multicellular stages or form
colonies
Not all eukaryotic cells have a nuclei, give two examples
Mature erythrocytes lack nuclei but most non-mammalian vertebrates have nucleated rbcs. Lens fibre cells in the eye have no nuclei
Roughly how many mitochondria do hepatocytes have per cell? This account for how much of the cell volume?
Around 2000, 20% of the cell volume
Liver cells need a lot of mitochondria because
they require energy for various processes, metabolism, chemical reactions and protein synthesis
Some eukaryotic cells have no mitochondria such as the
red blood cells
Mature lens fibre cells have no nuclei, no mitochondria and no ER, WHY?
Lens transparency through the formation of an organelle free zone
What is special about the mitochondria in sperm cells?
Contain a spiral mitochondria wrapped around the flaggelum
How does the number of mitochondria in the midpiece of the sperm relate to the feritlity?
The more mitochondria the greater the fertility
Which cells should contain the most abundant golgi?
Cells active in protein synthesis
