specialisation and organisation of cells Flashcards
how do cells become specialised
some genes are expressed with others are silences (turned off) due to cell differentiation mediated by transcription factors
cells produce proteins that determine their structure and function
what are the 2 groups of specialised cells in blood
erythrocytes - red blood cells = biconcave, no nucleus, lots of haemoglobin to carry oxygen
phagocytes - neutrophils and macrophages
how do the specialised cells in the blood form
multipotent stem cells in the bone marrow differentiate into erythrocytes (which has a short lifespan and cannot undergo mitosis since they have no nucleus ) and leucocytes including neutrophils
state the relationships between a system and specialised cells
specialised cells - tissues that have a specific function - organs made several tissue types - organ system
describe the structure and function of squamous epithelia
→ function: facilitate the diffusion of gases e.g. O2 and CO2 and small molecules
→ cells have a flattened and thin shape forming a one cell thick layer → therefore a short diffusion distance = faster rate of diffusion
the cells fit together tightly like a pavement (held together by a basement membrane) - large SA = faster rate of diffusion
define organ system
a group of organs that work together to perform a complex and essential function for the organism - respiratory system
define an organ
2 or more different tissues working together to perform a specific set of functions for the body e.g. heart
define a tissue
group of the same cells (or similar cell types) that are all adapted to carry out a particular function e.g. epithelia
define cells
cell differentiate to form specialised cells, that are adapted to perform a specific set of tasks/functions
describe the structure + function of ciliated epithelia
→ columnar epithelium cells
function:
→ to waft mucus and trapped pathogens/dust/debris along the airways towards the stomach or the nose
→ lines the airways of the respiratory system and the airways of the reproductive system
adaptation:
→ cilia are 10 um long hair-like motile processes, made of microtubules anchored in a basal body
→ they cyclical bending and straightening action causes the cilia to beat, moving mucus containing trapped particles e.g. dust and pathogens and microbes out of the lungs or egg along the fallopian tube to the uterus
→ mucus used to trap microbes are excreted from goblet cells
cilia have a lot more mitochondria compared to squamous
need energy/ATP
describe the specialised structure and function of erythrocytes
→ function: designed to transport oxygen and carbon dioxide around the body
adaptations:
→ gene switched on for the protein haemoglobin. Haemoglobin is a pigment that joins with oxygen
→ biconcave flattened discs. Has no nucleus non REWR to increase SA for maximum haemoglobin and therefore oxygen uptake
→ large surface area to volume ratio (7.5um diameter, 2.0um thick)
→ short diffusion distance to centre of cell and faster rate of diffusion of gases
→ really flexible so they can squeeze through narrow blood vessels
→ discard mitochondrion - no aerobic respiration so doesn’t use the oxygen they transport
→ contains an enzyme called carbonic anhydrase that catalyses the conversion of carbon dioxide with water to carbonic acid.
what are neutrophils
a type of white blood cells
describe the specialised the structure and function of neutrophils
function: destroy pathogen by phagocytosis and the secretion of enzyme (immune system)
→ large nucleus to synthesise proteins/enzymes (lysosomes/digestive enzymes)
→ many lobes - can change shape for phagocytosis
→ darkly stained
→ granular cytoplasm
→ 10-14 um diameter
what do you recognise a neutrophil
lobed nucleus
why are sperm cells mortile
the tail helps propel them forward in search of an egg to fertilise
describe the specialised structure of a sperm (spermatozoon)
function → reproduction to fuse with an egg cell and initiate the development of an embryo and pass on the fathers genes
the contains a nucleus that contains half the normal number of chromosomes (haploid, no chromosome pairs)
the acrosome in the head contains digestive enzymes that can break down the outer layer of an egg cell so that the haploid nucleus can enter to fuse with the egg’s nucleus
the mid-piece is packed with mitochondria to release energy (via respiration) for the tail movement
has a flagellum (9+2 arrangement) propelling the sperm cell forward and allowing to move towards the ovum
how many specialised animal cells and what are the names
erythrocytes
phagocytes - macrophages and neutrophils
what are the 4 specialised animals tissues and what are their names
squamous epithelium
ciliated epithelium
cartilage
muscles
what level of organisation are ciliated epithelial and squamous epithelial cells
tissues
name 3 types of muscle in the body and where they are located
cardiac → exclusively found in the heart
smooth → walls of blood vessels and intestines
skeletal → attached to incompressible skeleton by tendons
why can’t mature red blood cells divide by mitosis
they do not have a nucleus
what is the function and adaptation of phagocytes (macrophages)
function: ingest and destroy pathogens
macrophage adaptation
- large nucleus to synthesis
- proteins/enzymes (lysosomes /digestive enzymes)
- slightly lobed
- lighter stained
- non-granular cytoplasm
- size - 21um
- occupies < (less than) 70% cell
what are the function(s) and adaptations of the egg cell
→ function: to allow for fertilisation and support for the growth of the early embryo
→ large SA:V ratio
→ cytoplasm contains nutrients for growth of the developing embryo
there is an outer layer called the zona pellucida - this changes after fertilisation so that no further sperm can penetrate
→ follicle cells outside the zona pellucida form a protective coating around the egg cell
