cell structure Flashcards
what are centrioles
a component of the cytoskeleton
made of microtubules
involved in organisation of spindle fibres during cell division (2 centrioles = centrosome)
what are mitochondria
oval shaped organelles
the site of respiration - respiratory enzymes are found on cristae
able to produce own enzymes and reproduce themselves due to presence of mitochondrial DNA
what is the nucleus
comprised of nucleolus, nucleoplasm and nuclear envelope with nuclear pores (these allow substances to move between nucleus and cytoplasm e.g. RNA)
contains genetic information encoded as DNA molecules, stored as chromosomes
controls all activity within the cell
what is the nucleolus
contained within nucleus
contains chromatin (which is made when DNA associates with histone proteins) and ribosomal DNA
facilitates ribosome biogenesis
site of transcription
what is the rough endoplasmic reticulum
a system of membranes with ribosomes attached to it around a fluid filled space
folds proteins and packages them into vesicles
what is the smooth endoplasmic reticulum
a system of membranes around a fluid filled space
synthesises and processes lipids
what are ribosomes
a small organelle where proteins are made during protein synthesis
the site of translation
can be found attached to the RER or floating freely in the cytoplasm
what is the golgi body
a group of flat fluid filled sacs, sometimes seen with vesicles on the edge
modified and packages new proteins and lipids
produces lysosomes
what are lysosomes
specialised vesicles
round organelles containing digestive/hydrolytic enzymes
membrane keeps enzymes separate from the cytoplasm
these enzymes enable lysosome to digest invading cells or break down worn components of the cell
what is the cell wall
made of cellulose in plants and chitin in fungi and peptidoglycan in bacteria
a tough + elastic wall that supports + surrounds the plant cell
freely permeable
also ats as a defense mechanism against pathogens
what are chloroplasts
contains an internal network of thylakoid membranes
these membranes form flattened sacs called thylakoids
these stack to form granum
contain chlorophyll pigments used in light dependent stage of photosynthesis
what are plasmodesmata
narrow thread of cytoplasm surrounded by cell wall that connect the cytoplasm of adjacent plant cells
allows communication and transfer of substances between cells
what is a vacuole
a permanent membrane (called the tonoplast) lined sac containing cell sap
helps to maintain turgor pressure against cell wall
the tonoplast contains water protein channels called aquaporins that control water flow in and out of the vacuole
tonoplast is selectively permeable
what is a flagellum
long hair like structures that stick out of the cell surface
surrounded by plasma membrane
9+2 microtubule arrangement, these contract to make flagellum move - this requires energy
what is the slime capsule
a layer around the cell wall of the cell wall of a bacterial cell
mostly made of carbohydrate compounds e.g. polysaccharides/glycoproteins/glycolipids
protects cell from physical and chemical attacks
sticky so promotes cell adhesion - a survival advantage
protects cell from phagocytosis
