2.5 The ultrastructure of plant cells Flashcards
Plant cells, unlike animal cells, are what?
rigid structures
What make plant cells rigid structures?
they had a cell wall surrounding the cell-surface membrane
Plant cell walls are made of what?
cellulose, a complex carbohydrate
Cell walls are what so that substances can pass into and out of the cell?
freely permaable
The cell walls of a plant cell gives the cell its what?
shape
What makes a plant cell rigid?
The contents of the cell press against the cell wall
What does the rigidity of the plant do?
support both the individual cell and the plant as a whole
The cell wall, other than making the cell rigid, acts as a what?
a defence mechanism, protecting the cointents of the cell against invading pathogens
Not all plant cells have cellulose cell walls. True or false
False
What are vacuoules?
membrane lined sacs in the cyotoplasm containing cell sap
What do vacuoules contain?
cell sap
Many plant cells have large permanent vacuole which are very important for what?
the maintenance of turgor, so that the contents of the cell push against the cell wall and maintain a rigid framework for the cell
What is the result of the maintenance of the turgor from large permanent vacuoles
the contents of the cell are pushed against the cell wall and maintains a rigid framework for the cell
The membrane of a vacuoule is called the what?
tonoplast
The membrane of a vacuoule is what kind of permeable and why?
selectively- some small molecules can pass through it but others cannot
If vacuoules appear in animal cells, describe them
they are samll and transient (not permanent)
What are chloroplasts responsible for?
photosynthesis in plant cells
Where are chloroplasts found
in the green parts of the plant
-leaves stems but not in roots
What kind of structure does chloroplasts have?
double membrane structure (similar to mitochondria)
What is the stroma in chloroplasts?
the fluid enclosed in the chloroplast
What contains the chlorophyll pigments
the grana (several thylakoids stacked together)
Chloroplasts also have an internal network of what and what do they do?
network of membranes, which form flatted sacs called thylakoids
several thylakoids stacked together are called?
granum (plural grana)
the grana are joined by?
membranes called lamellae
starch produced by photosynthesis is present as?
starch grains (found inside chloroplast)
like mitochondria, chloroplasts also contain..
DNA and ribosomes
Chloroplasts and mitochondria have their own DNA and ribosomes, so therefore are able to?
make their own proteins
The internal membranes of chloroplasts provide what?
the large surface area needed for the enzymes, proteins and pigment molecules necessary in the process of photosynthesis
2a) Many different oganisms have cell walls including fungi and bacteria. What is unique about plant cell walls?
-plant cell walls contain cellulose
2b) Give three functions of plant cell walls
- prevent cells bursting
- allows turgidity
- idea that keeps plants upright
- protects content of cells from invading pathogens
3) Describe the similarities and differences between a human cell and a plant root cell
- Both have a nucleus, cell surface membrane, mitochondria, ribosomes, golgi body, endoplasmic reticulum
- only plants have chloroplase, cell wall and large (central vacuoules)
- centrioles present in animal cells not not flowering plants
