2.4/2.5 EUKARYOTE CELL STRUCTURE/ULTRASTRUCTURE OF PLANTS Flashcards
1
Q
What is the nucleus?
A
- contains genetic info in the form of DNA
- DNA directs the synthesis of all proteins and controls the metabolic activities
- Contained within a double membrane called the Nuclear Envelope
- DNA is transcribed into RNA - exported via the nuclear pores
- DNA associates with proteins called histones to form chromatin (condense to form chromosomes)
2
Q
What is the nucleolus?
A
- area within the nucleus which is responsible for producing ribosomes
- composed of proteins and RNA (used to produce ribosomal DNA)
3
Q
What is the Mitochondria?
A
- site of final stages of cellular respiration (energy to ATP)
- has a double membrane (inner membrane is folded to form cristae [contains enzymes used in aerobic respiration] and fluid called Matrix)
- contains small amount of DNA
4
Q
What are vesicles?
A
- membrane sacs that have storage and transport roles
- have a single membrane with fluid inside
5
Q
What are Lysosomes?
A
- Specialised forms of vesicles that contain Hydrolytic Enzymes
- break down waste materials in cells
- important roles in the immune system
6
Q
What is cilia?
A
- hair-like extensions
- mobile/stationary
- important function in sensory organs
- mobile cilia beat in a rhythmic manner, creating a current
- there are two separate microtubules surrounded by 9 pairs of microtubules arranged like a “wheel”
- 9 + 2 arrangement, pairs slide over each other (beating motion)
7
Q
What is Flagella?
A
- enable cells mobility
- whip-like structure
- used as a sensory organelle detecting chemical changes in the environment surrounding the cell
8
Q
What is the Endoplasmic Reticulum?
A
- network of membranes enclosing flattened sacs called Cisternae
- connected to the outer membrane of the nucleus
9
Q
What is the Smooth ER?
A
- Responsible for lipid and carbohydrate synthesis and storage
10
Q
What is the Rough ER?
A
- has ribosomes bound to the surface
- responsible for the syntheses and transport of proteins
11
Q
What are ribosomes?
A
- can be free floating in the cytoplasm or attached to the RER
- not surrounded by a membrane
- constructed of RNA
- site of protein synthesis
12
Q
What is the Golgi Apparatus?
A
- similar in structure to the SER
- compact structure formed of Cisternae, does not contain ribosomes
- modifies proteins and “packages” them into vesicles
13
Q
What is the Cellulose Cell Wall?
A
- cellulose is a complex carbohydrate
- freely permeable to substances can pass into/ out of the cell
- gives it shape
- rigid
- acts as a defence mechanism, protecting contents against pathogens
14
Q
What is the vacuole?
A
- membrane lined sacs in the cytoplasm containing cell sap
- large permanent vacuoles (important in the maintenance of turgor)
- membrane = tonoplast which is selectively permeable
- if appear in animal cells, they are small and transient
15
Q
What are chloroplasts?
A
- photosynthesis in plant cells
- green parts of the plant
- double membrane structure
- fluid is enclosed and is called the Stoma
- internal network of membranes, form flattened sacs called Thylakoids (several stacked together called a Granum)
- The Grana are joined by membranes called Lamellae the grana contain Chlorophyll Pigments
- Chloroplasts also contain DNA and ribosomes, can also make proteins
