DNA and cells - EUKARYOTES Flashcards
What kingdoms are eukaryotic?
Animals, plants, fungi, protoctists
Compare and contrast eukaryotic and prokaryotic cells
- E have a nucleus, membrane bound organelles and mitochondria whereas P don’t
- E are found in animals, plants, fungi and protoctista whereas P are in bacteria
- In E ribosomes are larger than P (80s vs 70s)
- E have linear DNA whereas P have circular DNA(plasmids)
What do plant cells have that animals cells don’t?
Chloroplasts, cell wall, vacuole
What is the nuclear envelope and what does it do?
- A double membrane with ribosomes on the surface surrounding the nucleus
- It controls entry and exit
What are nuclear pores and what do they do?
- Tiny holes on the surface of the nuclear envelope
- They allow passage of large molecules e.g.mRNA/ribosomes
What is nucleoplasm?
- The cytoplasm of the nucleus
What is the nucleolus and what does it do?
- Synthesises RNA
Describe the structure of the mitochondria
- Rod shaped
- 1-10µm in length
- Has a double membrane which controls entry and exit
- The inner membrane forms extensions/cristae
- The cristae has a large surface area for attachment of enzymes
- The matrix is gel-like which contains proteins, lipids, ribosomes, DNA and respiratory enzymes
What is the function of the mitochondria?
- Site of respiration
- Production of ATP
What is the function of the nucleus?
- Acts as the control centre of the cell through production of m/tRNA
- Holds genetic material (long term)
- Manufactures rRNA and ribosomes
What are ribosomes?
- Small organelles found in the cytoplasm
- Associated with the rough endoplasmic reticulum
- Involved in protein synthesis
Describe the structure of a ribosome
Made of rRNA and proteins/amino acids
Describe the structure of the cell membrane
- Composed of a phospholipid bilayer
- Has receptors which allow it to interact with other proteins, helping with cell recognition and signalling
What does the cell membrane do?
Controls the movement of substances into and out the cell
Describe the structure of the cytoplasm
- Jelly like substance which surrounds organelles
- Contains dissolved molecules that take part in metabolic reactions
What is the function of the cytoplasm?
- Contains dissolved molecules
- Site of chemical reactions
Where are lysosomes most commonly found?
In secretory cells
What is the structure of a lysosome?
- Formed of a hydrolytic enzyme mixture surrounded by a lipid layer and a membrane
- Also contains enzymes that hydrolyse cell walls of bacteria
What is the function of a lysosome?
- Aids secretion
- Hydrolyses material ingested by phagocytic cells
- Releases enzymes
- Digests old/damaged cells
- Completely breaks down cells after they have died
What is the difference between smooth and rough endoplasmic reticulum?
- Rough endoplasmic reticulum has ribosomes on the surface whereas Smooth endoplasmic reticulum don’t
- Smooth endoplasmic reticulum has a tubular appearance
Describe the structure of the endoplasmic reticulum
- Continuous with the nuclear envelope
- It is a network of tubules/ flattened sacs called cisternae
What is the function of the rough endoplasmic reticulum?
- Provides the pathway for transport of materials
- Has a large surface area for protein synthesis
What is the function of the smooth endoplasmic reticulum?
- Synthesises, stores and transports lipids/carbohydrates
Describe the structure of the golgi apparatus?
- A stack of membranes (looks like naan bread)
- Modifies proteins as they are passed through
What is the primary function of the golgi apparatus?
- Lipids are added to make lipoproteins
- Carbs are made into glycoproteins
- Polypeptides are made into proteins
What is the secondary function of the golgi apparatus?
- Produces secretory enzymes
secrete carbs, transport/modify/store lipids and form lysosomes
What is the structure of a chloroplast?
- Chloroplast envelope - has a double plasma membrane(highly selective
- Thylakoids - contains chlorophyll
- Grana - stacks of 100 disk shaped thylakoids
- Stroma - fluid filled matrix which contains enzymes, starch grains, DNA and ribosomes
What is the function of the chloroplasts?
Site of photosynthesis
What are adaptations of the chloroplasts?
- Granal membranes provide large surface area for attachment of chlorophyll
- Fluid contains enzymes
- Chloroplasts contain DNA + ribosomes for quick and easy manufacture of proteins.
Are chloroplasts found in plant cells, animal cells, or both
Plant cells only
Describe the structure of the cell wall
- Microfibrils of cellulose(matrix)/chitin in fungi
-Strong because of fibrils
-Thin layer called lamella marks the boundary between adjacent cells
What is the function of the cell wall?
To provide strength (especially during osmosis)
Is the cell wall found in plant cells, animal cells, or both?
Plant cells only
Is the vacuole found in plant cells, animal cells, or both?
Plant cells only
Describe the structure of a vacuole
- Fluid filled sac bounded by a single membrane called the tonoplast
What does the vacuole contain?
- Mineral salts
- Sugars
- Amino acids
- Metabolic wastes
- Pigments
What is the function of the vacuole?
- Maintains cell turgidity
- Contains an energy store and can contain pigments that make petals coloured (in order to attract pollinating insects)
