Cells Flashcards
What did Matthias Schleiden and Theodor Schwann propose in 1883?
That all plants and animals were made up of cells
What did Rudolf Virchow propose in 1855?
New cells could only arise from the division of pre-existing cells and the chemical reactions of life took place within the cell
4 principles of the modern cell theory
All living things are made up of cells
New cells are formed by the division of pre-existing cells
Cells contain genetic material, which is passed on from parent to daughter cells
All metabolic reactions take place inside the cell
Organisms made up of just one cell
Unicellular
Organisms made up of more than one cell
Multicellular
Differences between prokaryotic cells and eukaryotic cells
Prokaryotes do not have a nucleus or membrane bound organelles
Eukaryotes have genetic material in the nucleus whereas prokaryotes have a main chromosome of DNA called a nucleoid and small rings of DNA called plasmids
Examples of eukaryotes
Animals, plants, fungi
Examples of prokaryotes
Bacteria
Differences between plant and animals cells?
Plant cells also have a cellulose cell wall, plasmodesmata, chloroplasts, large permanent vacuoles but they do not have centrioles
Functions of the cell wall
Provide support for the cell by allowing it to become turgid
Provide mechanical strength to the cell
They are freely permeable to water and substances in solution
The cell walls of adjacent cells are glued together by?
Middle lamella, a jelly like substance made up of calcium pectate and magnesium pectate
What membrane is bound by the tonoplast?
The vacuole in plant cells
What does the vacuole of a plant cell contain?
Cell sap which is a solutions of sugars, amino acids, mineral salts and waste chemicals dissolved in water
Functions of the plant vacuole?
Water enters the vacuole by osmosis
Act as stores for foods like sugar and amino acids
Accumulate waste products
Some contain coloured pigment to give the plant colour
What does the nucleus contain?
DNA
What is the nucleus surrounded by?
Nuclear membrane, it is a double membrane with space in between
What is the name of the material inside the nucleus?
Nucleoplasm. It contains chromatin (made up of DNA) attached to proteins called histones
What does the nucleolus make?
rRNA and assembles ribosomes
Functions of the nucleus?
DNA contains genetic information for synthesis of proteins
Genetic material of the nucleus controls metabolism of the cell
Produces new chromosome material at cell division so each daughter cell is genetically identical
Why does haemoglobin not contain a nucleus?
To save space to enable them to carry more oxygen
What are the fluid filled spaces in the endoplasmic reticulum called?
Cisternae
Function of the cisternae?
A system of passages to allow materials to be transported throughout the cell
Rough endoplasmic reticulum contain ……. on its surface?
Ribosomes
Main function of roughy endoplasmic reticulum
To package and transport proteins made by ribosomes
Proteins are transported via the cisternae to vesicles to the Golgi body
RER can also produce pieces of new plasma membrane for the cell
Function of smooth endoplasmic reticulum
Synthesis of lipids and steroids
Transport of material through the cell in vesicles
Where are ribosomes found?
Free in the cytoplasm or on the rough endoplasmic reticulum
Ribosome function?
Protein synthesis
How are Golgi bodies formed?
Small pieces of rough endoplasmic reticulum are pinched off the ends to form small vesicles. These vesicles then join together
Functions of the Golgi body?
Modification of proteins and lipids from ER
Packaging finished proteins into vesicles for transport
Production of lysosomes
How are lysosomes formed?
When small vesicles are pinched off the Golgi body
Functions of lysosome?
Release enzymes called lysozyme that destroy worn out organelles
Digest material that has been taken into the cell this is call phagocytosis
Release their enzymes outside of the cell to destroy other cells this is called a exocytosis
Can cause the cell the self-destruct called autolysis
Functions of the mitochondria’s double membrane
Outer membrane control entry and exit of material
Inner membrane forms many folds called cristae where ATP is made
Functions of the matrix of the mitochondria
Contains enzymes needed for respiration. Also contains DNA and ribosomes so mitochondria can replicate themselves when the cell divides
Main function of the mitochondria
Aerobic respiration, converting glucose to a form of energy that can be used by the cell
Structure of the chloroplast?
Double membrane
Inner membrane forms stacks of flattened stacks called thylakoids, each stack is called a granum
Fluid cavity called stroma
Can contain starch grains (amyloplasts)
What is the cytoskeleton made up of?
Fibrous proteins such as microtubules, microfilaments and intermediate filaments
Functions of the cytoskeleton
To provide and internal framework to support the cell
Organise and move organelles within the cell
Move the whole cell
Construct the spindle during cell division
Provide the components of cilia and flagella
Microtubules are made up of?
Tubulin
Microfilaments are made up of?
Actin
Structure of the cell membrane?
Semi-permeable to control movement of substances in and out of the cell
Bilayer of phospholipids
The phospholipid bilayer has ……. heads and …….. tails
Hydrophilic heads and hydrophobic tails
How do substances enter the nucleus?
Through the nuclear pores
What is chromatin?
Long strands of DNA wrapped around purple histone proteins to organise the DNA and keep it compact in the nucleus
The nuclear envelope is attached to?
The rough endoplasmic reticulum
Ribosomes are made up of?
Two subunits
What type of ribosomes do eukaryotes have?
80s and 70s within mitochondria and chloroplasts
What type of ribosomes do prokaryotes have?
70s
Why do mitochondria and chloroplasts replicate their own DNA?
They were originally separate prokaryotes but evolution saw them become part of the eukaryote cell
What side of the Golgi does the vesicle from the ER arrive?
Cis face
What side of the Golgi does the vesicle containing the finished protein leave?
Trans face
Function of microtubules?
Enables organelles to move through the cytoplasm, aided by motor proteins
Forms the spindle during cell division
Part of the centrioles, cilia and flagella
Function of microfilaments?
Enables cells to move and change shape e.g. when cells divide
Function of the intermediate filaments?
Mechanical strength
Structure of the centriole?
Part of cytoskeleton
Found as a pair at right angles to each other
Arranged in a ring of 9 sets of triplet microtubules
No membrane
Function of centrioles?
Organise the spindle during cell division
Make cilia and flagella
Structure of cilia?
Part of cytoskeleton
Made of microtubules- 9 pairs plus a pair in the middle, 9+2 formation
Function of cilia?
Waft things along, e.g. mucus in respiratory tract or egg in Fallopian tube
Sense chemical changes in environment
The only animal cell that has flagella?
Sperm cell
Structure of flagella in animal cells?
9+2 formation of microtubules
Only one or two per cell
Function of flagella in animal cells?
Allow the cell to move with a whip-like movement
What are prokaryotic flagella made of?
Protein called flagellin
Difference in function of prokaryotic and eukaryotic flagella?
Prokaryotic flagella moves the whole organism in a propeller like movement whereas eukaryotic flagella just moves that cell in a whip-like movement
Function of the chloroplasts?
Photosynthesis, thylakoids contain chlorophyll to absorb sunlight
What is a plant cell wall made of?
Cellulose, carbohydrate in a mesh
What is a fungi cell wall made of?
Chitin, containing sugars and nitrogen
What is a bacteria cell wall made of?
Peptidoglycan, containing proteins and sugars
Where does aerobic respiration in a prokaryote take place?
Not proven for certain but it is believed to be in the mesosome, a folded area of surface membrane
Where is the DNA in a prokaryote?
Circular DNA in the nucleoid region, not membrane bound. Can also be in small plasmid rings in cytoplasm
How can plasmids influence antibiotic resistance?
Antibiotic resistance genes are often found in plasmids and plasmids can be moved from one prokaryote to another
Function of the cell capsule?
Keeps the cell hydrated as it retains moisture
Can help the cell to evade recognition by the host e.g. pathogens
Function of Peroxisome?
Similar to lysosomes but contain oxidative enzymes. They digest fatty acids, ethanol and amino acids
Structure of Peroxisome?
Small membrane bound
Contains oxidative enzymes
