1.2 Cells as the Basic Units of Living Organisms Flashcards
Cell surface membrane
structure and functions (3)
surrounds cell (7nm thick)
partially permeable and controls the movement of substances into and out of the cells
allows cells to interact with each other and receive signals
Nucleus
structure and functions
(3)
in cytoplasm
contains DNA coding for the synthesis of proteins in the cytoplasm
surrounded by a double membrane (nuclear envelope)
nucleolus
structure and functions
(2)
one to several in nucleus
synthesises ribosomal RNA and makes ribosomes
Rough endoplasmic reticulum
structure and functions
(3)
throughout cytoplasm
covered with ribosomes
membrane –> enclosed compartments that transport proteins synthesized on the ribosomes
Smooth endoplasmic reticulum
structure and functions
(3)
In cytoplasm
similar to rough ER but no ribosomes
synthesis transports lipid molecules
Golgi Body
structure and functions
(4)
In cytoplasm
synthesis glycoproteins (proteins with carbohydrate groups attached)
packages proteins for export from the cell
mitochondria
structure and functions
(2)
in cytoplasm
produce (ATP) by aerobic respiration
ribosomes
structure and functions
(4)
attached to rough ER or free in cytoplasm
site of protein synthesis
80S in the cytoplasm
70S in chloroplasts and mitochondria
lysosomes
structure and functions
in cytoplasm
digests unwanted materials and worn out organelles
centrioles
structure and functions
(4)
two hollow cylinders in animal cells
lie next to the nucleus
made of protein microtubules
exact function unknown
microtubules
structure and functions
(2)
attached to rough ER or free in cytoplasm
involved in movement of the cells
chloroplast
structure and functions
(3)
in cytoplasm of some plant cells
contain chlorophyll
site of photosynthesis
cell wall
structure and functions
(3)
layer surrounding plant cells
made of cellulose
regulate movement of water
plasmodesmata
structure and functions
(3)
pores in plant cell wall
contain fine strands of cytoplasm linking plant cell with neighboring cells
allows movement of materials between cells
vacuole
structure and functions
large central space in plant cells
contains solutes like sugars and mineral salts
surrounded by a membrane: tonoplast
tonoplast–> controls exchange of materials between the vacuole and cytoplasm
cells use ATP
from respiration for energy - requiring processes
key structural features of a prokaryotic cells found in typical bacterium
(6)
Unicelluar
generally 1-5 um in diameter
peptidoglycan cell walls
circular DNA
70S ribosomes
absence of organelles surrounded by double membranes
compare the structure of a prokaryotic cell found in a typical bacterium with the structures of typical eukaryotic cells
All viruses are ___
non-cellular structures with a nucleic acid core (either DNA or RNA)
What is the function of the nucleolus?
(wrong test answer)
a) the formation and breakdown
b) the formation of rough endoplasmic reticulum
c) synthesis of ribosomal proteins
d) the synthesis of rRNA
D
Bacteria are unicellular prokaryotic cells with a diameter of 1-5 um
State two other structural features that would identify a cell as prokaryotic
(wrong test answer)
circular DNA
plasmid
70S ribosomes
absence of membrane bound organelles
Formed from microtubules during mitosis
(wrong test answer)
spindle
Has peptidoglycan as one of its major components(wrong test answer)
prokaryotic cell wall
Site of assembly of 80S ribosomes
(wrong test answer)
nucleolus
Bacterial cells are what kind of cell?
Prokaryotic cells
Outline the key features of viruses. (4)
acellular structures
contain nucleic acids (either RNA or DNA) surrounded by a protein coat known as a capsid. The capsid can have attachment proteins to gain access to host cells.
viruses possess no organelles or ribosomes and so rely on host cells to synthesise the components of viral particles
some viruses may have a phospholipid envelope surrounding the capsid. HIV
How does the structure of the smooth endoplasmic reticulum (SER) differ from that of the rough endoplasmic reticulum (RER)?
the SER does not have ribosomes on its outer surface
Name the membrane surrounding the large permanent vacuole
The tonoplast
name the main constituent of plant cell walls
cellulose
Describe the structure of chloroplasts
Chloroplasts have a double membrane and contain a fluid called stroma. Within the chloroplast, thylakoids are arranged into interconnected stacks of grana. They also contain 70S ribosomes and circular DNA.
What is a cilium
A cilium is a hair-like structure that projects from a cell. The cilium may be able to move (motile) or be stationary (non-motile)
What are the two types of ribosome, and where are they found?
80S ribosomes are found in eukaryotic cells - in the cytoplasm and on the RER
70S ribosomes are found in prokaryotic cells, chloroplasts and mitochondria
What are lysosomes?
Vesicles from the Golgi body that contain digestive enzymes
eg: proteases, lipases and lysozymes
What is the function of the smooth endoplasmic reticulum?
The SER synthesises and transports lipids
What are the roles of the nucleus? (3)
To store the genetic material (DNA) of the cell
to synthesise ribosomes
to regulate production of messenger RNA for protein synthesis
State the function of the large permanent vacuole (3)
stores cell sap, which contains sugars, pigments and wast substances
role in maintaining turgor pressure
acts as a temporary food store
