eukaryotic cell structure Flashcards
how to differentiate between plant and animal cells
animal : centrioles, microvilli
plant : cellulose cell wall, large permanent vacuoles, chloroplast
function of nucleus
contains dna, direct sythesis of proteins
controls metabolic activities of the cell
dna in nucleus associates with proteins histones, form chromatin, chromatin coils and condenses to form chromosomes
function of nucleolus
produce ribosomes
composed of proteins and RNA (produce ribosomal RNA, form ribosomes)
function of nuclear envelope
protects DNA from damage in cytoplasm
contains gaps called nuclear pores, allows molecules to move in and out of nucleus
structure of mitochondria
2-5 um long
has double membrane, inside is highly folded, forms structure called cristae
centre is fluid called matrix
have small circular pieces of DNA (mtDNA)
contain ribosomes
function of mitochondria
site of cellular respiration, release energy for cell to use
can produce their own enzymes and reproduce themselves (self-replicating)
structure of ribosomes
about 20nm diameter
found attached to rough ER or floating free in cytoplasm
constructed of RNA molecules produced in nucleolus
composed of 2 subunits - small and large (combine after they leave the nucleus)
not surrounded by membrane
in mitochondria and chloroplasts
in all prokaryotic and eukaryotic cells
function of ribosomes
site of protein synthesis
function of cell surface membrane
boundary of all cells
controls what enters and exits the cell
structure of cell surface membrane
made of a phospholipid bilayer
partially permeable
fragile
function of golgi apparatus
stores, modifies and packages proteins into vesicles
molecules transported to and from the golgi by vesicles
protein modification [adding sugar molecules=glycoprotein/ adding lipid molecules = lipoproteins]
folds proteins in 3D shape and package proteins into vesicles
structure of golgi apparatus
similar to smooth endoplasmic reticulum
compact structure formed of cisternae
looks like a stack of plates
structure of endoplasmic reticulum
a network of membranes enclosing flattened sacs called cisternae
connected to the outer nuclear membrane
structure of rough ER
ribosomes bound to the surface
function of rough ER
processes proteins made by ribosomes
structure of smooth ER
no ribosomes
function of smooth ER
lipid [cholesterol and steroid hormones] and carbohydrate synthesis and storage
structure of vesicles
membranous sacs with storage and transport roles
single membrane with fluid inside
function of vesicles
transport materials inside the cell
function of lysosomes
hydrolytic enzymes to break down waste material in the cell, including old organelles and pathogens ingested by phagocytic cells
plays an important role in programmed cell death [apoptosis]
structure of lysosomes
a specialised type of vesicle that contain hydrolytic enzymes
what is microtubules
one of three part of cytoskeleton
function of microtubules
form cilia, undulipodia and centrioles
structure of cilia and undulipodia
extensions protruding from some cells which provide motility
function of cilia and undulipodia
provide motility
can be stationary[nose] / mobile [trachea]
structure of cilia
hair-like
each cilium contain 2 microtubules surrounded by 9 pairs of microtubules arranged like a wheel [9+2 arrangement]
function of cilia
move substances outside of human cells
beat in a rhythmic manner, creating a current
structure of undulipodia
whip-like extensions
found on sperm cells
function of undulipodia
used as a sensory organelle detecting chemical changes in the cell’s environment
function of centrioles
aid in cell division by migrating to opposite ends of cells [organisation of spindle fibres in animal cells]
structure of centrioles
found in animal cells [some simple plant cells], can only be seen during cell division
hollow fibres made of microtubues, a type of proteins and part of the cytoskeleton of the cell
what is centrosome
two centrioles at right angles to each other
function of centrosome
organise spindle fibres during cell division
structure of chloroplast
4-10 um long
double membrane
fluid [stroma {light dependent stage } ] enclosed
have internal network of membranes which form flattened sacs called thylakoids
several thylakoids stacked together = granum
grana contain chlorophyll pigments, light dependent stage
internal membranes provide large surface area to volume ratio ,needed for enzymes,proteins and pigment molecules necessary in the process of photosynthesis
contain DNA and ribosomes
function of chloroplast
absorb light, catalyst for photosynthesis
can self-replicate and make their own proteins
structure of cell wall
located outside of the cell membrane
freely permeable
contents of the cell press against the cell wall
made of cellulose in plants [fibre]
contains gaps called plasmodesmata, connecting one cell to the next, allows for movement of substances between cells
plant [cellulose]
fungal [chitin]
bacterial [peptidoglycan]
function of cell wall
provide a rigid, protective barrier
provide structural support
structure of vacuoles
large, central vacuole in plant cells
many smaller in animal cells, not permanent
bound by tonoplast
function of vacuoles
storage container for water, food, enzymes, waste, pigments
