Cell Structure and Organsisation Flashcards
What is the function of the nucleus?
It retains the genetic information (DNA) which codes for protein synthesis
What is the nuclear envelope and its function?
A double membrane with pores to allow the transport of mRNA and ribosomes out of the nucleus
What is the function of the nucleolus?
To synthesise ribosomal RNA (rRNA)
What is the function of mitochondria?
To release energy in the form of ATP during aerobic respiration
The inner membrane of a mitochondrion is folded inwards creating extensions called _______
Cristae
What is the function of cristae in a mitochondrion?
Increase the surface area for ATP synthesis to occur
What is the function of ribosomes?
Site of protein synthesis
What is the function of the rough endoplasmic reticulum?
Protein synthesis and transport of proteins
What is the function of the smooth endoplasmic reticulum?
Synthesis and transport of lipids
What are the 3 main functions of the Golgi apparatus?
- modifying and packaging proteins into secretory vesicles for secretion from the cell
- producing glycoprotein
- forming lysosomes
What is the function of lysosomes?
- release hydrolytic (digestive) enzymes when the cell needs to break down worn out organelles
- digest material that has been taken into the cell
What are the 4 structural components of the cell membrane?
- PHOSPHOLIPIDS (forming bilayer)
- PROTEINS
- CARBOHYDRATES (glycolipids and glycoproteins)
- CHOLESTEROL (animal cells)
Why is it called the fluid mosaic model?
FLUID: individual phospholipid molecules can move around relative to one another
MOSAIC: proteins embedded in the bilayer vary in size and are arranged in a random pattern
Function of phospholipids in cell membrane
Form selective bilayer that allows non polar/uncharged molecules through but prevents the passage of polar/charged molecules
Function of extrinsic proteins in cell membrane
Associated with one layer only. May act as receptors for hormones
Function of intrinsic proteins in cell membrane
Act as channels to allow the passage of polar molecules eg glucose
Function of glycocalyx in cell membrane
Act as cell to cell recognition
Function of cholesterol in cell membrane
Controls membrane fluidity
What is the function of centrioles?
Animal cell only
During cell division, they migrate to opposite poles of the cell and form the spindle
What are plasmodesmata and what is their function?
Narrow pores in the cell wall. Fine strands of cytoplasm pass through these connecting one cell to the next, allowing substances to move between them.
Why do chloroplasts contain circular DNA?
For self replication
What is the function of chloroplasts?
The site of photosynthesis
What is the endosymbiotic theory?
Organelles such as chloroplasts and mitochondria were originally free living prokaryotic cells
What is a prokaryote?
Single celled organisms lacking membrane bound organelles, such as nuclei, with DNA free in the cytoplasm
What is a eukaryote?
Organism made of cells that have membrane bound organelles with DNA within the nucleus in the form of chromosomes
Why is a virus not considered living?
They do not have organelles, enzymes, chromosomes or cytoplasm.
What is the name of a virus that attacks bacteria?
Bacteriophages
What is a virus made up of?
Nucleic acid, surrounded by a protein coat. Some have DNA while others contain RNA
What 4 ways can viruses be transmitted?
- aerosol
- insect vectors
- exchange of bodily fluids
- bites
What is the definition of an organism?
All the systems of the body working together make an organism, which is a discrete individual
What does unicellular mean?
Single celled organisms which carry out all life functions within one cell
What does multicellular mean?
Organisms consisting of many specialised cells which form tissues and organs, which have various structures and roles
What is differentiation?
The process by which a stem cell becomes specialised into a specific type of cell
What is division of labour?
The adaptation of different parts of an organism to carry out different functions. The more advanced the organism the greater the division of labour.
Define a tissue
An aggregation of specialised cells carrying out a specific function
What are the 4 primary tissue types in the human body?
- Epithelial tissue
- Muscle tissue
- Connective tissue
- Nerve tissue
Name the 4 types of epithelial tissue and give an example of where they are found
- Squamous epithelium (mouth, alveoli)
- Cuboidal epithelium (kidney tubules, ducts of glands)
- Columnar epithelium (stomach, intestines)
- Ciliated columnar epithelium (trachea, oviduct)
What are the 3 muscle tissue types?
- Cardiac
- Skeletal
- Smooth
Define an organ
An aggregation of several tissues that carry out a specific function for the whole organism
Define an organ system
2 or more different organs working together to provide a common function
What are the 5 plant tissues?
- Xylem
- Phloem
- Palisade mesophyll
- Spongy mesophyll
- Upper epidermis
What is the function of the xylem?
Transport of water and dissolved minerals
What is the function of the phloem?
Transport of sucrose and amino acids (photosynthates)
What is the function of the palisade mesophyll?
Photosynthesis
What is the function of the spongy mesophyll?
Some photosynthesis, it provides air space for diffusion of gases in/out of the leaf
What is the function of the upper epidermis?
Contains cells that are found on the top surface of a leaf, protected by a waterproof waxy cuticle
Define chromatin (found in the nucleus)
Coils of DNA bound to histone proteins
