cell structure and organisation

Question 1

cell theory states that:

Answer 1

• new cells are formed from other existing cells
  -the cell is a fundamental unit of structure, function and organization in all living organisms

Question 2

what are prokaryotic cells?

Answer 2

the first ever type of cell which is found in domains of bacteria and the dna is not enclosed in a cell membrane.

Question 3

what are the organelles found in prokaryotic cells?

Answer 3

plasma membrane, pili, peptidoglycan cell wall, cytoplasm, capsule, flagellum, small ribosomes, circular dna, mesosome

Question 4

what 3 organelles are only present in some prokaryotic cells?

Answer 4

pili, capsule, flagellum

Question 5

what are eukaryotic cells?

Answer 5

these are believed to have evolved from prokaryotic cells though, the dna is contained inside a nuclear membrane, they are larger and have more and some different organelles.

Question 6

what organelles does prokaryotic bacteria contain?

Answer 6

plasma, membrane, ribosomes, vacuoles, mesosome, dna, cellwall

Question 7

eukaryotic animal cells contian?

Answer 7

plasma membrane, nuclear membrane, membrane bound organelles (e.g mitocondria) ribosomes, vacuoles, centrioles and dna

Question 8

what do eukaryote plant cells contain?

Answer 8

plasma membrane, nuclear membrane, membrane bound organelles (e.g mitocondria) ribosomes, vacuoles, chloroplast, DNA, cell wall

Question 9

what is difference between ribosomes in prokaryotic bacteria cells and eukaryotes animal and plant cells?

Answer 9

prokaryotic - small and free in cytoplasm
eukaryotic plant and animal- large free in cytoplasm and attached to rough ER.

Question 10

What is the difference between vacuoles in prokaryotic and eukaryotic plant and animal cells?

Answer 10

prokaryotic- small and temporary
eukaryotic animal cells- small and temporary
eukaryotic plant cells - large, permanent vacuole surrounded by tonoplast membrane.

Question 11

why do scientists believe that viruses are not cells or alive?

Answer 11

-no cell membrane
- no cytoplasm
-cant do respiration or synthesis atp
- dont grow
-cant replicate or reproduce (invade host cell and use metabolic processes)

Question 12

what are basic components of a virus?

Answer 12

-protein coat (capsid)
-enzymes involved in viral replication
- a molecule of dna or rna: contains a small number of genes which code for essential viral proteins.

Question 13

function of nucleus?

Answer 13

contains DNA of cell

Question 14

function of nucleolus?

Answer 14

inner part of nucleus and begins assembly of ribosomes

Question 15

function of chloroplast?

Answer 15

captures energy from light for photosynthesis

Question 16

function of golgi apparatus/ body?

Answer 16

modify, sort and ship proteins and lipids

Question 17

function of mitochondria?

Answer 17

makes ATP energy during aerobic respiration

Question 18

function of ribosome?

Answer 18

creates polypeptide chains and proteins

Question 19

function of smooth endoplasmic recticulum?

Answer 19

create lipids for cellular membrane

Question 20

function of rough endoplasmic recticulum?

Answer 20

proteins are assembles and transported into/ out of the cell

Question 21

function of lysosome?

Answer 21

uses enzymes to breakdown old organelles and macromolecules

Question 22

functions of vacuole?

Answer 22

stores water, salts and carbohydrates

Question 23

function of cytoskelenton?

Answer 23

helps maintain its shape and involved in movement

Question 24

function of cytoplasm?

Answer 24

material inside cell membrane but outside nucleus

Question 25

function of centriole?

Answer 25

help organize cell division

Question 26

function of cell wall?

Answer 26

give plants extra structure and stability

Question 27

function of cell membrane?

Answer 27

controls what enters and exits cell

Question 28

the components of the nucleus

Answer 28

-bounded by two membranes, nuclear envelope and pores which allow the passage of large molecules e.g mRNA and ribosomes out of the nucleus.
- the granular material in the nucleus is the nucleoplasm. it contains chromatin which is made of coils of DNA bound to protein. during cell division, chromatin condenses into chromosomes
-in the nucleus there are one or more small spherical bodies called nucleolus. these are sights of formation of rRNA- constituent of ribosomes

Question 29

mitochondria comprise of:

Answer 29

-two membranes, seperated by a narrow fluid filled inter membrane space. the inner membrane is folded inwards to form cristae.
- an organic matrix, containing many compounds like lipids and proteins
- small circle of DNA so mitochondrion can replicate and code for some of its proteins and RNA
-small (70s) ribosomes which allow protein synthesis

Question 30

which type of cells contain a lot of mitochondrion

Answer 30

metabolically active cells e.g muscle cells as they need plentiful supply of ATP

Question 31

what does the cristae do in the mitochondrion

Answer 31

provide large surface area for attachment of enzymes involved in respiration

Question 32

chloroplast structure consists of:

Answer 32

-two membranes
- the stroma(includes products to do photosynthesis)
- contain 70s ribosomes and circular dna

Question 33

what is the endosymbiotic theory

Answer 33

describes the origin of chloroplast and mitochondria. it was seen to closely resemble cyanobacteria. its also been suggested mitochondria was an independant bacteria

Question 34

what is exocytosis?

Answer 34

involved the secretion of substances from cells. adds new membrane by fusion of vesicles from inside the cell with the plasma membrane, so increases the surface are of the plasma membrane

Question 35

what is endocytosis?

Answer 35

takes in substances/food particles by surrounding particles and infolding of the plasma membrane to form phagocytic vesicles. this removes membrane from the plasma membrane and decreases the surface area of the plasma membrane

Question 36

how do the endoplasmic reticulum, golgi body and the plasma membrane work together

Answer 36

• to enable cells to take in large food particles (including bacteria) and then to digest them internally
• to synthesise, process and package enzymes and them release them to an exterior of a cell for external digestion

Question 37

protein synthesis involves:

Answer 37

-in the nucleus: the transcription of the genetic code in the DNA into messenger RNA (mRNA)
-in the nucleolus: production of ribosomes
-the nuclear pores: the mRNA leaves the nucleus and enters the cytoplasm through nuclear pores.
-in the cytoplasm: ribosomes translate of the code in mRNA into polypeptides(amino acids bonded together with peptide bonds)
- in RER: a vesicle pinches off the RER and transports polypeptide to the golgi body
-in the golgi bodies: the processing of the polypeptides to produce functional proteins (folding to give secondary/tertiary structure, adding carbohydrate chains, combining polypeptides) and packaging of the proteins into secretory vesicles for secretion

Question 38

how do cells become specialised in multicellular organisms

Answer 38

according to the functions they preform leading to division of labour

Question 39

what is a tissue

Answer 39

a tissue is an aggregation of similar cells carrying out the same function e.g layer of cells that cover the alveoli is epithelial tissue