2.1.1 Cell Structure Flashcards
1
Q
What are eukaryotic cells?
A
Cells that contain membrane bound organelles
2
Q
What is the nucleus?
A
- Site of DNA replication and transcription
- Contains genetic code for each cell
- Surrounded by a nuclear envelope (double membrane)
- Outer membrane is continuous with the RER
- Pores allow mRNA and ribosomes out and nutrients and hormones in
- Chromosomes are in a loosely coiled state (chromatin)
- The nucleolus is the site of ribosome synthesis
3
Q
What is the rough endoplasmic reticulum?
A
- Intracellular transport system made up of extensive membranes present within cytoplasm
- Studded with ribosomes
- Large SA for ribsomes
- Ribosomes make proteins which are then transported within the ER’s cisternae
4
Q
What is the smooth endoplasmic reticulum?
A
- Contains enzymes involved with lipid metabolism (synthesis of lipids/phospholipids and synthesis of cholesterol
- Storage site for calcium in skeletal muscle cells
- Involved with absorption, synthesis and transport of lipids from the gut
5
Q
What is the golgi apparatus?
A
- A series of tightly packed, flattened sacs (cisternae)
- Collects and processes proteins
- Made from vesicles budded (from ER) which fuse at forming face
- Vesicles bud off from maturing face to go to surface membrane for secretion or to form lysosomes
6
Q
What is the plasma membrane?
A
- Has a triliminar appearance
- Selectively permeable
- Controls entry and exit of materials
- Made of phospholipid bilayer
7
Q
What is the vacuole?
A
- Large fluid filled sac
- Surrounded by a membrane called the tonoplast
- Only plant cells have a permanent vacuole
- Filled with water and solutes
- Provides support by creating a pressure potential through osmosis
- Pressure means cells become turgid
8
Q
What are the mitochondria?
A
- Rod like structures with a double membrane
- The inner membrane is highly folded to form cristae which project into the matrix
- Completes the later stages of aerobic respiration and synthesizes ATP
- Self replicating and abundant in metabolically active cells
- DNA loop codes for enzymes needed for enzymes
9
Q
What is the chloroplast?
A
- Organelle only found in plant cells
- Surrounded by a double membrane
- Inner membrane is continuous with thylakoids which run through stroma
- Thylakoids are stacked (grana)
- Site of photosynthesis
- Grana trap light energy used to fix carbon dioxide in the stroma
- Stroma contain enzymes for photosynthesis
10
Q
What are the ribosomes?
A
- Made of protein and rRNA
- Site of protein synthesis
- Two sizes (70s is smaller ribosome found in prokaryotes and 80s is a large ribosome found in eukaryotes)
- Attached to RER or free in the cytoplasm
11
Q
What are the lysosomes?
A
- Contain powerful hydrolytic enzymes for hydrolysis
- Single membrane
- Enzymes are kept separate from rest of the cell
- Role is to destroy damaged cells and organelles
- Present in white blood cells and acrosome of sperm head in large numbers
12
Q
What are the cilia?
A
- Membranous cellular extensions
- Move in a wave like manner
13
Q
What is the centriole?
A
- Pair of centrioles are present just outside the nucleus at right angles to each other
- Triplets of microtubules form a ring
- Microtubules are made from tubulin
- Produce spindle fibres which attach to centromere of chromosome in cell division
14
Q
What is the cell wall?
A
- High tensile strength to prevent the cell from bursting when turgid
- Maintains cell shape
- Contributes to structural strength and support of plant
- Freely permeable
- Cellulose in plants
- Chitin in fungi
- Peptidoglycan in prokaryotes
15
Q
What is the flagella?
A
- A whip like structure
- Aids mobility
