cytology Flashcards
what is a cytosol
largely water but also sugars proteins and salts.
viscous liquid
what are inclusions
various substances found in some cells but not others
e.g melanin in retinal pigment epithelium.
what are microfilaments
help in migration process and phagocytosis
what are microtubuls
form cillia
hair like appendages on the surface of many cells
move gluid
what does a nucleoplasm contain
chromatin and nucleolus within a matrix
what is the structure of a nucleotide
deoxyribose
phosphate
base (4)
what is a gene
dna that codes for the production of a particular protein
what are coding portions of dna called
exons
what is the size of muscle cells
2 micrometres
what is the size of muscle cells
30 cm
what is the size of nerve cells
1 m
what does a general cell consist of
plasma memrane
cytoplasm
organelles
nucleus
what are the functions of cell membrane
integrity of cell:
- not generally permeable
- surfaces of epithelial cells have different permeabilities.
specific regulation of passage:
-specific and selective gates
communication site:
-receptors for molecules such as hormones
what are integral proteins
span the plasma membrane
act as gates
act as receptors
what are peripheral proteins
co enzymes
help function of proteins
what is the function of membrane proteins?
- transport
- enzymatic activity
- receptors for signal
- transduction
- intercellular joining
- cell-cell recognition
- attachment to the cytoskeleton and extracellular matrix
What is Glycocalyx?
sugar coating of the cell attached mainly to integral proteins
- enables sperm to recognize egg cell
- signals which cells should be destroyed by phagocytosis
- determines ABO blood group of red blood cells
what are the three different types of junctions between cells
- sticky glycoproteins on cell surface (glue)
- mechanical junctions
- specialised cell-cell junctions.
what are mechanical junctions
-ball and socket joint
-tongue and groove
between lens fibres
what are occluding junctions
- adjacent protein molecules in opposing plasma membranes fuse
- prevents the passage of molecules between cells.
what are anchoring junctions
adhering junctions or desmosomes
found in skin epithelium,
cardiac muscle and uterus.
very robust.
what are desmosomes
- plaques are anchored to the inside of the cell by intermediate filaments
- plaques of adjacent cells are linked by cadherins.
what is a belt desmosome
long way round the cell
what is hemidesmosome
plasma membrane to cytoplasm
what is a spot desmasome
small area.
macula adherens
what are gap junctions
adjacent cells joined by membrane proteins.
proteins allow cytoplasmic continuity so molecules can pass between cells
what are the junctions between membrane proteins in gap junctions known as?
connexons
where does the lens receive nutrients from?
aqueous humour
why are cells that make up the lens joined by gap junctions?
so nutrients can diffuse from the lens surface to cells in its interior.
what is a cytoskeleton and its function?
cell skeleton
gives shape
mediates cytoplasmic movements of organelles
what are intermediate filaments?
hold everything tgether
respond and change length
what does the centrosome in microtubules contain?
centrioles at right angles to each other
important for cell replication
what is the nucleus?
control centre
regular shape in normal cells
nuclear pores-selective movement of cells
where are ribosomes made?
nucleolus
what is the function of chromatin?
makes up our chromosomes
intertwined DNA and histone proteins
where is our genetic information stored?
chromosomes.
what are complimentary base pairs linked by?
hydrogen bonds
what is 1 amino acid coded for by?
codon
3 adjacent nucleotides.
what is transcription?
triplet codes of a gene are copied into a molecule of mRNA
what is translation?
mRNA combines with complimentary tRNA molecules join to form the protein.
what are synthesised proteins packaged by?
golgi apparatus
how many pairs of autosomes and sex chromosomes do we have?
22 pairs of autosomes
one pair of sex chromosome
