chapter 6 : cell division

what are the 3 main stages of the cell cycle

interphase (90%)

mitosis

cytokinesis

what are specialised cells

cells that have differentiated to perform a specific function

what is an erythrocyte

a red blood cell

contains haemoglobin which binds to oxygen to transport it from the lungs to body tissues

how are erythrocytes specialised to their role (3)

biconcave so increased surface area

no nucleus so more space for haemoglobin

flexible to allow passage through narrow capillaries

what is a neutrophil

a type of white blood cell involved in phagocytosis with a cytoplasm filled with lysosomes to break down phagocytosed material

where are erythrocytes replaced

are constantly being produced by bone marrow as they only have a lifespan of 120 days

where are neutrophils replaced

bone marrow

what is a cell

a specialised unit that has differentiated to carry out a specific function

what is a tissue

a collection of differentiated cells with a specialised function

what is an organ

a collection of tissues adapted to perform a particular function

what is an organ system

a number of organs working together to carry out a major function

what is an organism

a living entity that can function independently

what is the epidermis and what is it made of

the thin outer layer of the skin that consists of squamous cells basal cells and melanocytes

what are squamous cells

cells that make up the outermost layer which are continuously shed

what are basal cells

cells found at the base of the epidermis

what are melanocytes

cells found at the base of the epidermis that make melanin and gives skin its colour

what re 8 things the dermis consists of

blood vessels

lymph vessels

hair follicles

sweat glands

collagen bundles

fibroblasts

nerves

sebaceous glands

what is the role of collagen in the dermis

it holds the dermis together and gives skin flexibility and strength

where do specialised cells originate from

undifferentiated stem cells

what is a stem cell

a cell that can divide an unlimited number of times and develop into any cell

what is division in stem cells

stem cells divide by mitosis to produce new cells

what is differentiation

the process by which a stem cell becomes a specialised cell

what is potency

a level of how many types of cells stem cells can differentiate into

what are the 3 potencies

totipotent

pluripotent

multipotent

what is totipotent

can become any body cell including cells in placenta and umbilical cord (usually in zygotes)

what is pluripotent

can form any type of body cells but no placenta or umbilical cord (usually in embryos)

what is multipotent

can form more than one type of cell but not all types of body cells (adult stem cells, usually in bone marrow)

what is a blastocyst

a ball of cells that form during early pregnancy

why is differentiation important

groups of cells with different functions working together as one unit can make use of resources more efficiently that single cells operating on their own

what are embryonic stem cells

totipotent stem cells found in embryos

once embryos form a blastocyst stem cells become pluripotent

where are plant stem cells found

in meristems which is wherever growth is occurring

where is meristematic tissue found

shoots and roots

vascular cambium (between xylem and phloem tissues)

what is the potency of meristems

pluripotent but meristematic tissue in the vascular cambium typically differentiate into cells present in xylem and phloem

what are 7 diseases that have the potential to be treated using stem cells

heart disease

type 1 diabetes

parkinson’s disease

alzheimer’s disease

macular degeneration

birth defects

spinal injury

how are stem cells used to treat heart disease

muscle tissue that was permanently damaged as a result of a heart attack can be replaced

how is type 1 diabetes treated using stem cells

the body’s own immune system destroys insulin producing cells in the pancreas

stem cells can be used to make insulin producing cells

how is parkinson’s disease treated using stem cells

dopamine-producing cells are replaced which delays the progress of the disease and symptoms

how is alzheimer’s treated using stem cells

brain cells that are destroyed as a result of the build up of abnormal proteins are replaced to alleviate symptoms

what are 2 current uses of stem cells

replacing cells damaged from burns by growing them on biodegradable mesh

drugs are tested on stem cells before humans and animals

what are the ethical issues around embryonic stem cells

removal of stem cells from embryos normally result in the destruction of the embryos which lead to moral and religious objections

what is the function of squamous epithelium

allows for rapid diffusion

what is the structure of squamous epithelium

made up of many flat squamous epithelial cells

one cell thick so very short diffusion distance

what is the function of ciliated epithelium

prevents unwanted particles reaching alveoli in the lungs

what is the structure of ciliated epithelium

made of ciliated epithelial cells with hair like cilia

cilia wafts mucus (that’s released from goblet cells) away from the lungs

what is the function of cartilage

prevents end of bones rubbing together

can be structural (e.g. forms skeleton of some fish)

what is the structure of cartilage

a connective tissue made of chondrocyte cells embedded in an extracellular matrix composed of fibres of elastin and collagen

what is the function of muscle

allows movement by contracting

what is the structure of muscle

skeletal muscle fibres are made of myofibrils which contain contractile proteins

what is the structure of the epidermis

single layer of closely packed cells covered by a waxy cuticle to reduce water loss

what is the function of xylem

transports water and minerals throughout the plant

what is the structure of xylem

vascular tissue made of elongated dead cells strengthened by lignin

what is the function of phloem

transports organic nutrients throughout the plant

what is the structure of phloem

vascular tissue composed of columns of sieve tubes cells separated by perforated sieve plates

what is the structure of neutrophils

multi lobed nucleus to make it easier to squeeze through gabs to infection sites

granular cytoplasm contained lysosomes to attack pathogens

what is the structure of sperm

has a flagellum for movement

contains many mitochondria for energy

acrosome contains digestive enzymes which aids fertilisation

what is the function of root hair cells

uptakes water and minerals from soil

what is the structure of root hair cells

long extension near growing tips of the roots to increase surface area

what is the function of guard cells

allows carbon dioxide to enter the plant for photosynthesis

opens and closes to control water and oxygen loss and uptake

what is the structure of palisade cells

rectangular cells that can tightly pack together

thin walls to increase rate of diffusion of carbon dioxide

large vacuole to maintain turgor pressure

what is the role of palisade cells

contains many chloroplasts for photosynthesis