UNIT 2 - B 2.3 - Cell Specialization Flashcards
What allows multicellular organisms to grow and allows the replacement of dead/damaged cells?
cells having the ability to reproduce themselves
What do multicellular organisms usually start their existence as?
a single cell called a zygote
What is a zygote formed as a result of?
ferilization
What are gametes?
The two cells that fuse in sexual reproduction
How much genetic material does gamete have compared to a zygote?
one half
What is the development progression for humans?
gametes, zygote, embryo, foetus, infant
What does the process of zygotes rapidly starting to differentiate result in?
the formation of specialized cells
What is the differentiation process a result of?
the expression of some genes but not others
What does the cell’s development in a specific matter depend on?
which genes become active
What does the genes activation depend on?
the signal that the cell recieves
What is cell signaling?
The process where information is transferred from the cell surface to the nucleus of a cell
What is cell signalling essential to?
controlling gene expression/differentation
What are morphogens?
signal molecules that control cell differentiation
Where do morphogens occur?
in gradients in different regions of the early embryo
What controls the regional development of the first cells into head and tail structures?
The concentration of the signal molecules (morphogens)
What is different genes being expressed in different parts of the embryo a result of?
The gradient of the signalling molecule (morphogens)
What results in different genes being expressed in different parts of the embryo?
differnent parts of the embryo develop different features
What happens with signalling molecules as the embryo develops?
other signalling molecules become factors in differentiation
What are examples of types of cells that have a diminished ability to reproduce once they become specialized/lose ability all together?
nerve and muscle cells
What type of cells retain their ability to reproduce quickly throughout their life?
epithelial cells such as skin cells
What type of cells are formed from cells that rapidly reproduce?
The same type as the orginal cell
Which type of cells retain their ability to divide and differentiate into different types of cells?
Stem cells
What do stem cells’ ability to divide and differentiate along different pathways result in?
organisms to possess all the types of cells
Where are stem cells found in plants?
Regions of meristematic tissue
where is meristematic tissue found in plants?
near root and stem tips
What are meristematic tissues made of?
rapidly reproducing cells which become various types of tissues within the root or the stem
What do stem cells produce when they divide to form a type of tissue?
daughter cells which stay as stem cells
What is self-renewal?
a process that allows continual production of a type of tissue while also providing continuation of stem cells
What are the two unique properties of stem cells?
The can self-renew and they can recreate functional tissues
What are the possible outcomes of a stem cell dividing?
both daughter cells remain as stem cells, both a stem cell and differentiated cell are formed, or both cells are differentiated
When do cells become differentiated?
when cell signalling ensures that specific genes are expressed as the cell develops
What are stem cell niches?
locations where stem cells are present in high numbers but also demonstrate differentiation
What are examples of stem cell niches in humans?
bone marrow and hair follicles
In bone marrow, where are the stem cells that produce blood cells found?
alongside self-renewing stem cells
What transports differentiated cells away as blood cells are produced?
a large array of supporting blood vessels
Where do hair follicles exist?
in the skin
What are found in the bottom, rounded area of a hair follicle?
large numbers of epithelial stem cells
What are multipotent epithelial stem cells involved with?
hair growth, skin and hair follicle regeneration, the production of sebaceous (oil producing) glands associated with hair follicles
What are the different types of stem cells?
totipotent, pluripotent, multipotent, and unipotent
What are the main characteristics of totipotent stem cells?
they are capable of continued division, have the ability to produce any tissue in organism, only exist in early stages of embryo development, may form a complete organism
What are the main characteristics of pluripotent stem cells?
they come from totipotent cells, only exist in early embryonic stages, can become almost all cell types, cannot produce complete organism
What are the main characteristics of multipotent stem cells?
only forms a limited number of cell types, occur later in development of embryo, present during remainder of organism’s life
What is an example of multipotent tissue?
bone marrow tissue that produces different types of blood cells
What are the main characteristics of unipotent stem cells?
only forms a single cell type (sperm cells in mammals), they usually form late in embryonic stages, exist in the functioning organism
What is the problem when it comes to using stem cells to treat human diseases?
stem cells cannot be distinguished by their appearance
What is the only way for stem cells to be isolated from other cells?
based on their behavior
What does growing embryonic stem cells in cultures so they can be used to replace differentiated cell lose due to injury/disease involve?
therapeutic cloning
How could parkinson’s and alzheimer’s disease’s symptoms by relieved?
implanting stem cells that could replace many lost/defective brain cells
Why are sperm cells small?
Because the only carry out the function of transporting genetic material so that a viable zygote can be formed
What are the adaptations of red blood cells?
they contain haemoglobin that can combine with/release oxygen, they have a biconcave disc shape allowing more surface area for oxygen absorption, they lack both mitochondria and a nucleus, they are flexible and size limited so they can move through narrow blood capillaries
What are white blood cells’ main function?
defence against infection
Unlike red blood cells, what do white blood cells have through their whole life?
a nucleus
What do many white blood cells have that can kill microorganisms?
vesicles with appropriate enzymes
What are the enzymes in the vesicles in white blood cells also used in?
the breakdown of harmful cellular debris brought into the cell by phagocytosis
Why are white blood cells bigger than red blood cells?
becuase they have a nucleus, granules and mitochondria
What do motor neurons do allowing muscles to respond to stimuli?
they carry impulses from the brain/spinal cord
What allows motor neurons to carry impulses up and down the body over long distances?
long fibres called axons
What are striated muscle fibers?
specialized cells found in skeletal muscle
what is each muscle fiber also?
a muscle cell
What are the membranes surrounding muscle fibers capable of?
impulse propagation
How do striated muscle fibers produce movement?
by contracting/shortening
What is cell size largely dictated by?
basic processes of cell physiology and cell division apparatus
What happens if cells are too large or too small when it comes to cell division?
the mitotic spindle will not function properly
What limits the size a cell can reach?
the surface area-to-volume ratio
What functions of the cell depend on volume?
rate of heat and waste production and the rate of resource consumption
What does the size of the cell affect with chemical reactions?
the rate of reactions
What can a cell with more surface area per unit volume do?
move more material in/out of the cell for each unit volume of the cell
What happens as the width of the cell increases?
the surface area also increases though at a slower rate than the volume
What cells have less surface area to bring in materials to get rid of the waste?
a large cell compared to a small cell
What do modifications of larger cells allow the cells to do?
function efficiently when taking in gasses and nutrients, get rid of metabolic waste
What are the modifications that give more favourable surface area-to-volume ratios in cells?
changes in cell shape, cellular projections (in and out), location relative to sources of nutrients and means of transporting waste away, how the cells fit together at a specific location
What allows red blood cells to have a greater surface area-to-volume ratio?
The biconcave disc shape
What is erythrocytes?
red blood cell
What allows red blood cells to squeeze through small capillaries to deliver oxygen to cells of the body?
Their size and flexibility
What are the proximal convoluted tubule?
the cells lining the part of the human kidney
What are the adaptations of proximal convoluted tubule for?
increase their ability to reabsorb fluids and secrete ions
What are the adaptations of proximal convoluted tubule?
cube-shaped cells are closely packed together, they have microvilli, they have large numbers of mitochondria, they have channels on the opposite side of the cell to the lumen
What is the advantage of closely packed cells?
a more efficient use of space
What does the microvilli do?
they point outwards into the lumen of the tubule where fluid flows which creates a brush border and increases surface area
What do the large numbers of mitochondria in proximal convoluted tubule allow?
active transport of ions and other substances
What do the channels opposite of the cell to the lumen of proximal convoluted tubule do?
increase surface area to help transportation
What is the functional unit of the lungs?
the alveolus (alveoli)
what does the alveoli do to maximize gas exchange?
increase the surface area of the lung
Where are alveoli located?
at the end of the respiratory tract
What do alveoli look like?
empty sacs lined by a wall made up of a layer of single cells
What are the cell types covering the cell surface of each alveolus?
type I pneumocytes
type II pneumocytes
alveolar macrophages
What type of cell covers 95% of the alveolar surface?
type I pneumocytes
What is the main function of type I pneumocytes?
to allow gas exchange between the alveoli and capillaries
What are the adaptations of type I pneumocytes?
they are thin and flat to increase surface area and minimize diffusion distance, they share a basement membrane with the endothelium (lining) of lung capillaries which minimizes diffusion distances for respiratory gases, they are tightly joined to each other so that fluids cannot enter the alveoli from the capillaries
Which cell makes up less than 5% of the surface of the alveolus?
type II pneumocytes
Where are type II pneumocytes found?
between the type I pneumocytes
what is the function of type II pneumocytes?
to produce pulmonary surfactant
What does pulmonary surfactant do?
reduces surface tension and prevents the alveoli from collapsing and sticking to each other during the breathing process
What are the adaptations of type II pneumocytes?
a cube shape providing a larger cytoplasmic area for organelles producing surfactant, microvilli oriented towards the alveolar sac which increases surface area and allows more surfactant secretion, cytoplasm containing many organelles involved with surfactant production/secretion, the ability to transform into type I pneumocytes when needed
What do the different types of cells present in the lung allow?
many functions to be carried out efficiently
What are the adaptations of striated skeletal muscle cells?
a long, cylindrical shape
a membrane capable of impulse propagation
multiple nuclei (multinucleated)
visible bands capable of shortening to produce voluntary movement
What are the further adaptations of cardiac muscle fibres?
they are composed of branching, striated cells
they have a single nucleus per fibre/cell
they are connected at the ends by intercalated discs
What does the branching cells and connections between them allow cardiac muscle fibres to do?
coordinate a contractile process involving the whole heart to pump blood throughout the body
How do striated muscle fibres differ from normal cells?
they are longer than most animal cells an, do not follow the usual pattern of cell division, and they do not follow the usual process of cell death (apoptosis) followed by cell replacement when it is severely damaged
When do striated muscle fibres grow?
when their supporting satellite cells fuse with the existing fibres
How does the sperm cell adaptations differ from egg cell adaptations in terms of size?
sperm: one of the smallest human cells
egg: one of the largest human cells
How does the sperm cell adaptations differ from egg cell adaptations in terms of flagellum?
sperm: flagellum is present, allows motility, mitochondria located near flagellum to supply energy for movement
egg: no flagellum, cell is non-motile
How does the sperm cell adaptations differ from egg cell adaptations in terms of shape?
sperm: head and tail region and is stremalined for speed and efficiency
egg: non-streamlined, spherical shape
How does the sperm cell adaptations differ from egg cell adaptations in terms of cytoplasmic organelles?
sperm: very few cytoplasmic organelles, ex. ER, golgi apparatus, ribosomes
egg: most cytoplasmic organelles present plus specialized storage structures for initial embryo development
How does the sperm cell adaptations differ from egg cell adaptations in terms of their production?
sperm: continually produced in vast numbers throughout male life
egg: all early gamete-forming cells are present before birth, no new egg-forming cells are produced after birth
How does the sperm cell adaptations differ from egg cell adaptations in terms of vesicles?
sperm: head has specialized secretory vesicles (acrosomal vesicle) that helps the sperm penetrate egg’s outer coat
egg: has special secretory vesicles under plasma membrane that releases contents after one sperm penetrates the egg to prevent another from entering
What kind of nucleus do both sperm and egg cells contain?
a haploid nucleus
