Eukaryotic cells Flashcards
what is a cell surface/ plasma membrane?
a partially permeable phospholipid bilayer that surrounds all cells and controls the exchange of materials between the internal cell environment and the external environment.
what are the functions of the cell surface membrane?
-regulates movement of substances in and out of the cell.
-contains receptor molecules, allowing it to respond to chemicals such as hormones.
- allows cell compartmentalisation.
what is a cell wall?
a rigid structure that surrounds the outside of plant cells which is made of cellulose.
what is the function of the cell wall?
to provide structural support to the cell as well as shape and rigidity.
what is the nucleus?
an organelle which contains chromatin - a complex of DNA and histone proteins.
* contains the genetic material of the cell.
what is the main features of the nucleus
- present in all eukaryotic cells
- large
-double membrane bound (nuclear envelope) - nuclear pores which allow mRNA and ribosomes to travel out of the nucleus, as well as allowing enzymes and signalling molecules to travel in.
- contains chromatin which condenses to form chromosomes
- contains the nucleolus which produces rRNA
what is the function of mitochondria
ATP production through aerobic respiration.
what are the features of mitochondria?
- surrounded by a double membrane with the inner membrane folding to from cristae which increases surface area.
-matrix which is the internal fluids, contains enzymes needed for respiration.
-small circular pieces of DNA and ribosomes are also found in the matrix for replication.
what is the function of a chloroplast?
photosynthesis
what are the features of a chloroplast?
- surrounded by a double membrane
- contains membrane bound compartments called thylakoids (which contain chlorophyll) that stacks to form grana
- grana are joined together by lamellae
- all surrounded in a fluid called the stroma.
what is the function of a ribosome?
site of protein synthesis.
what are the main features of a ribosome?
- do not have a membrane
- free in the cytoplasm or attached to the endoplasmic reticulum
-consist of 2 subunits
-ribosomes use mRNA to assemble amino acids to from a protein using tRNA by reading codons and bonding aminos together.
what are the different types of ribosome?
80s- composed of 60s and 40s subunits are found in all eukaryotic cells
70s- composed of 50s and 30s subunits are found in prokaryotes and mitochondria and chloroplasts.
what is the role of the smooth endoplasmic reticulum?
lipid and carbohydrate synthesis
what are the main features of the SER
flattened membrane bound sac (cisternae)
does not have ribosomes
what is the role of the rough endoplasmic reticulum?
protein synthesis.
processes proteins made by the ribosomes
what are the main features of the RER
-surface is covered in ribsomes
- formed from continuous folds of membrane from the nuclear envelope.
-cisternae bound to ribosomes.
what is the role of the Golgi apparatus
modifies proteins and packages them into Golgi vesicles.
what are the main features of the Golgi
- flattened sacs of membrane
- has vesicles that transport proteins and lipids to where they’re required.
- the proteins are generally exported, put into lysosomes or delivered to organelles.
what is the role of a large permanent vacuole?
increases the turgor of a cell ( the extent the cell is filled with water) to increase support
what is the main features of a permanent vacuole?
- a sac in plant cells surrounded by the tonoplast.
what is the role of a lysosome?
to break down waste materials within the cell, such as worn out organelles.
- extensively used by the immune system and in apoptosis.
what is the main feature of a lysosome?
-specialist vesicles containing hydrolytic enzymes
what is the role of a centriole?
-organises microtubules for cell division
- forms flagella and cilia
what are the main features of a centriole?
- hollow fibres made of microtubules
- 2 centrioles at tight angles to each other form a centrosome which organises spindle fibres in division.
what is the role of microtubules?
make up the cytoskeleton of a cell
what are the main features of microtubules?
made of alpha and beta tubulin combined to form dimers which then joint to from protofilaments.
13 protofilaments create a microtubule
what is the role of cilia and flagella
allow movement
what is the main feature of both cilia and flagella
both have a cylinder containing 11 microtubules: 9 in a circle and 2 in the centre.
what is the role of microvilli?
increase the surface area of the cell surface for increased rate or exchange.
how can an animal be identified under a microscope?
lysosomes, centrioles and microvilli are only present in animal cells
how can a plant cell be identified under a microscope?
cell walls, vacuoles and chloroplasts are only present in plant cells.
What is a plastid
A membrane bound organelle found in plant cells that have a specialised function
