Cells Part One Flashcards
(29 cards)
What are Eukaryotic cells?
- Eukaryotic means “true nucleus”
- They have a nucleus which contains the DNA
- Eukaryotic animal cells are surrounded by a cell membrane
- Inside is the jelly like substance called cytoplasm.
- Contained in the cytoplasm is the nucleus and other organelles which are membrane bound
- The other cell organelles include the endoplasmic reticulum,(rough & smooth) mitochondria, Golgi apparatus, ribosomes, lysosomes, centrioles, cilia, nucleolus.
What is the function of the Endoplasmic reticulum?
- Forms an extensive transport system
- Site of protein synthesis (Rough ER)
- Site of lipid and carbohydrate synthesis (smooth ER)
- Stores and transports these materials
What is the structure of the Endoplasmic reticulum?
Complex system of sheet like double membranes continuous with the nuclear membrane
Fluid filled spaces/sacs between the membranes called cisternae which allow materials to be transported through the cell
Two types of ER:
Smooth- has no ribosomes attached (SER)
Rough- has ribosomes attached (RER)
What is the function of the Golgi apparatus?
- Modifies protein
- Packages proteins into vesicles to be transported to where they are needed.
What is the structure of the Golgi apparatus?
- A sack of membrane bound sacs.
- Small vesicles can be ‘pinched’ off the Golgi apparatus carrying new chemicals which are secreted when the vesicle reaches the cell membrane.
What is the function of a ribosome?
Protein synthesis
What is the structure of a ribosome?
- Small dense structures found in huge numbers
- Can be attached to the rough ER or floating in the cytoplasm
- Are about 20-25nm in diameter in eukaryotic cells(70s type- eukaryotic)
- Made up from two subunits (large and small)
- No membrane
What is the function of a Lysosome ?
- Release enzymes which destroy worn out organelles
- Digests material taken into the cell (e.g. white blood cells which have engulfed a bacterium)
- Releases enzymes to the outside of the cell which digest material around the cell
What is the structure of a Lysosome?
- Small spherical membrane
- Contains hydrolytic enzymes which digests materials in the cell
What it the function of Mitochondria?
- Site of aerobic respiration
- The numbers of mitochondria reflect the metabolic activity of the cell- so large numbers are found in the muscle and liver cells
What is the structure of Mitochondria?
- Relatively large organelle
- Rod/sausage shaped- 1um - 5um
- Have a double membrane
- The outer controls the entry & exit of material
- Inner has many folds called cristae
- Mitochondria are filled with a jelly like matrix
What is the function of the Plasma membrane?
- Controls movement substances in & out of the cell
- Forms a recognition site so that so that the body’s immune system can recognize its own cells
- Acts as a receptor site for the attachment of specific hormones and neurotransmitters
What is the structure of the Plasma membrane?
- This is the boundary between the cell cytoplasm and the environment
- It is partially permeable
- Made up 45% protein & 45% phospholipids with the remaining 10% cholesterol, glycoprotein & glycolipids
What is the function of the Nucleus?
- Acts as the control centre of the cell through protein synthesis
- Retains the genetic material in the cell in the form of DNA / chromosomes (chromatin)
- The nucleus manufactures ribosomal RNA & ribosomes
What is the structure of the Nucleus?
- Largest organelle in the cell
- Surrounded by a nuclear membrane /envelope
- Double membrane- outer membrane joins with the ER
- Nuclear pores in the membrane allow the passage of large molecules in & out
- A spherical structure called the nucleolus is found in the nucleus- this makes the ribosomes and molecule called DNA
What is the structure of Centrioles?
- Two short bundles of hollow cylinders (microtubules) positioned at right angles to each other
- Found just outside the nucleus in a clear area of the cytoplasm
- During cell division they migrate (move) to opposite poles to produce the the spindle- which helps to move the chromosomes during the cell division
What is protein synthesis?
Protein synthesis is the process where by biological cells generate new proteins; it is balanced by the loss of cellular proteins via degradation or export.
Where does protein synthesis happen?
Protein synthesis occurs in cellular structures called ribosomes , found outside the nucleus. The process by which genetic information is transferred from the nucleus to the ribosomes is called transcription. During transcription, a strand of ribonucleic acid (RNA) is synthesized.
What is the function of transport and secretory vesicles?
- Transport vesicles take the protein to the golgi apparatus.
- Secretory vesicles take the protein from the golgi apparatus to the cell membrane.
How are plant cells different to animal cells?
- All cells have cytoplasm, a nucleus and a cell membrane.
- Plant cells have also a cell wall, a central vacuole and in many cases, chloroplasts.
- Animal cells do not have these structures, but they do have centrioles.
What can be found in a plant cell?
- Chloroplast
- Chromosome
- Smooth endoplasmic reticulum
- Amyloplast
- Large central vacuole
- Tonoplast
- Cell wall
- Nuclear membrane
- Golgi apparatus
- Mitochondrion
What are Prokaryotic cells?
- Prokaryotic means ‘before nucleus’
- Prokaryotes are single-celled organisms that do not contain nuclei.
- The cells are between 1-5μm in size and are much smaller than eukaryotic cells.
- Their ribosomes are smaller and are known as 70S.
Where in the bacterial cell can you find the DNA?
Most bacteria contain small independent pieces of DNA called plasmids that often encode for traits that are advantageous but not essential to their bacterial host.
What is transcription?
The process of transcribing RNA, with existing DNA serving as a template, or vice versa.
