eukaryotic cell structure

Question 1

how to differentiate between plant and animal cells

Answer 1

animal : centrioles, microvilli
plant : cellulose cell wall, large permanent vacuoles, chloroplast

Question 2

function of nucleus

Answer 2

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

Question 3

function of nucleolus

Answer 3

produce ribosomes
composed of proteins and RNA (produce ribosomal RNA, form ribosomes)

Question 4

function of nuclear envelope

Answer 4

protects DNA from damage in cytoplasm
contains gaps called nuclear pores, allows molecules to move in and out of nucleus

Question 5

structure of mitochondria

Answer 5

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

Question 6

function of mitochondria

Answer 6

site of cellular respiration, release energy for cell to use
can produce their own enzymes and reproduce themselves (self-replicating)

Question 7

structure of ribosomes

Answer 7

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

Question 8

function of ribosomes

Answer 8

site of protein synthesis

Question 9

function of cell surface membrane

Answer 9

boundary of all cells
controls what enters and exits the cell

Question 10

structure of cell surface membrane

Answer 10

made of a phospholipid bilayer
partially permeable
fragile

Question 11

function of golgi apparatus

Answer 11

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

Question 12

structure of golgi apparatus

Answer 12

similar to smooth endoplasmic reticulum
compact structure formed of cisternae
looks like a stack of plates

Question 13

structure of endoplasmic reticulum

Answer 13

a network of membranes enclosing flattened sacs called cisternae
connected to the outer nuclear membrane

Question 14

structure of rough ER

Answer 14

ribosomes bound to the surface

Question 15

function of rough ER

Answer 15

processes proteins made by ribosomes

Question 16

structure of smooth ER

Answer 16

no ribosomes

Question 17

function of smooth ER

Answer 17

lipid [cholesterol and steroid hormones] and carbohydrate synthesis and storage

Question 18

structure of vesicles

Answer 18

membranous sacs with storage and transport roles
single membrane with fluid inside

Question 19

function of vesicles

Answer 19

transport materials inside the cell

Question 20

function of lysosomes

Answer 20

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]

Question 21

structure of lysosomes

Answer 21

a specialised type of vesicle that contain hydrolytic enzymes

Question 22

what is microtubules

Answer 22

one of three part of cytoskeleton

Question 23

function of microtubules

Answer 23

form cilia, undulipodia and centrioles

Question 24

structure of cilia and undulipodia

Answer 24

extensions protruding from some cells which provide motility

Question 25

function of cilia and undulipodia

Answer 25

provide motility can be stationary[nose] / mobile [trachea]

Question 26

structure of cilia

Answer 26

hair-like each cilium contain 2 microtubules surrounded by 9 pairs of microtubules arranged like a wheel [9+2 arrangement]

Question 27

function of cilia

Answer 27

move substances outside of human cells beat in a rhythmic manner, creating a current

Question 28

structure of undulipodia

Answer 28

whip-like extensions found on sperm cells

Question 29

function of undulipodia

Answer 29

used as a sensory organelle detecting chemical changes in the cell’s environment

Question 30

function of centrioles

Answer 30

aid in cell division by migrating to opposite ends of cells [organisation of spindle fibres in animal cells]

Question 31

structure of centrioles

Answer 31

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

Question 32

what is centrosome

Answer 32

two centrioles at right angles to each other

Question 33

function of centrosome

Answer 33

organise spindle fibres during cell division

Question 34

structure of chloroplast

Answer 34

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

Question 35

function of chloroplast

Answer 35

absorb light, catalyst for photosynthesis can self-replicate and make their own proteins

Question 36

structure of cell wall

Answer 36

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]

Question 37

function of cell wall

Answer 37

provide a rigid, protective barrier provide structural support

Question 38

structure of vacuoles

Answer 38

large, central vacuole in plant cells many smaller in animal cells, not permanent bound by tonoplast

Question 39

function of vacuoles

Answer 39

storage container for water, food, enzymes, waste, pigments