3.2.1.1 eukaryotic cells Flashcards
what are some characteristics of eukaryotic cells?
NUCLEUS - membrane bound and contains genetic information.
MEMBRANE BOUND ORGANELLES - like mitochondria, chloroplasts, permanent vacuoles.
what are some key structures of the nucleus?
- nuclear envelope.
- nuclear pores.
- chromatin.
- nucleolus.
what is the nuclear envelope?
- separates the nucleus from the cytoplasm by a double membrane.
- controls the entry and exit of molecules protecting DNA from damage.
why are the nuclear pores important?
as they allow channels for mRNA and ribosomes to travel out of the nucleus as well as allowing enzymes in.
what is chromatin?
a material from which chromosomes are made.
- chromosomes are made from sections of linear DNA wrapped around histone proteins.
what is the nucleolus?
- a dense region of DNA and protein.
- site of ribosome synthesis.
what is the function of mitochondria?
site of aerobic respiration.
what’s special about mitochondria’s membrane?
- surrounded by a double membrane, with an inner and outer membrane.
- inner membrane folded to form cristae = large surface area for attaching proteins in the finial stages of aerobic respiration.
what is the fluid in mitochondria?
- the matrix is the ‘mitochondrial fluid’.
- formed by the cristae containing enzymes needed for aerobic respiration, producing ATP.
how is mitochondria prepped for replication?
- has circular pieces of DNA (mitochondrial DNA) and 70S ribosomes in the matrix.
what are the membrane bound, chlorophyll containing components in chloroplasts?
- thylakoids, which stack to form structures called grana.
- grant are joined together by lamella.
what is the function of chloroplasts?
site of photosynthesis.
- light-dependant stage takes place in the thylakoids.
- light-independent stage takes place in the stroma.
what is present in the chloroplast fluid stroma?
small circular pieces of DNA & 70S ribosomes used to synthesise proteins needed in chloroplast replication and photosynthesis.
what is the cell surface membrane made of?
phospholipids and proteins, which form the bilayer, and are constantly in motion.
what is the role of the cell surface membrane?
to control the exchange of materials between the internal cell environment and external cell environment.
= described as partially permeable.
how does the phospholipid bilayer work in the cell surface membrane?
- contains embedded proteins and glycoproteins and transport proteins.
- bilayer is hydrophobic = only small and non polar molecules can diffuse across it.
- transport proteins select which molecules can cross the membrane and proteins/glycoproteins which can fuse with other membranes and control the attractions.
what is the function of the cell wall?
- formed on the outside of the cell membrane and offers structural support to cell.
- acts as a barrier to pathogens/ external factors, protecting cell from external risks.
how can plant cell walls connect to other plant cells?
narrow threads of cytoplasm (plasmodesmata) connects the cytoplasm of neighbouring cells = providing mechanical strength.
how else can cell walls provide mechanical strength?
- made of cross linked cellulose fibres embedded in a matrix.
- provides mechanical strength to prevent cells from bursting due to osmotic pressure.
what is the middle lamellae in cell walls made of?
pectin and login.
what are the cell walls in plant cells made of?
cellulose
what are the cell walls in fungi cells made of?
chitin
what are the cell walls in algae made of?
cellulose and glycoproteins.
what is the function of the Golgi apparatus?
- modifies proteins and lipids before packing them into Golgi vesticles.
= transports proteins and lipids to their required destination. - proteins are either exported, put into lysosomes or delivered to membrane bound organelles.
what are Golgi vesticles?
- membrane bound sacs for transport and storage.
- transports large molecules of exocytosis or to add to different organelles.
- secrete materials from cells.
what type of enzymes does lysosomes contain?
- hydrolytic enzymes.
- enzymes that break biological molecules down.
whats the function of lysosomes?
- breaks down waste material such as worn out organelles
- used extensively by cells of the immune system and in apoptosis (programmed cell death).
- digests pathogens and large molecules ingested into cell.
what are ribosome formed from?
equal parts rRNA (ribosomal RNA) and protein.
where can ribosomes be found?
found freely in the cytoplasm or as part of the rough endoplasmic reticulum.
what type of ribosome can be found in eukaryotic cells verses in prokaryotic, mitochondria and chloroplasts?
eukaryotic = 80S ribosomes.
prokaryotic, mitochondria and chloroplasts = 70S ribosomes.
what is the function of ribosomes?
site of translation = protein synthesis.
what are the two types of endoplasmic reticulum?
rough endoplasmic reticulum and smooth endoplasmic reticulum.
what are some structural differences between SER and RER?
RER = surface covered in ribosome, creating a large surface area.
SER = doesn’t have ribosomes and large interlinked network of tubules of membranes.
BOTH = formed from continuous fold of membrane continuous with the nuclear envelope.
what is the function of RER?
- processes proteins made by ribosomes.
- synthesis of proteins for transport in vesicles.
- synthesis of proteins which form parts of membrane.
what is the function of SER?
- involved in the production, processing and storage of lipids, carbohydrates and steroids.
what is the membrane of vacuoles?
tonoplast membrane - selectively permeable membrane.
what is the function of vacuoles?
- temporary food store.
- helps maintain tutor pressure.
