B2,3 Cell Specialization Flashcards
Fertilization
The fusion of a male and female gamete to produce a zygote.
Zygote
The single-celled product of human gamete fusion.
Embryo
The product of continuous the cell division of a zygote, a mass of cells.
What’s the role of mitosis in cell division?
Ensures that the embryo has all the genes in the genome, so it can specialize/develop in any way.
Differentiation
A process by which cells develop along different pathways and become specialized for specific functions in the development of an embryo.
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How do morphogens contribute to embryo cell differentiation?
- Concentrations of morphogens indicate to a cell its position in the embryo and which pathway it should follow.
- They determine which genes are transcribed to produce mRNA and which proteins are made in each cell.
Give an example of the presence of morphogens:
Gradients of morphogens between the anterior and posterior of early-stage embryos.
What are the properties of stem cells?
They are self-replicating cells who are undifferentiated, and therefore retain the capacity to differentiate along different pathways.
What gives stem cells power in regeneration/repair in adult bodies despite their small percentage?
They are present in many human tissues.
The stem cell niche
The precise location of stem cells within a tissue that must provide the microenvironment required for them to remain undifferentiated for long periods of time or to proliferate rapidly.
Bone marrow
Soft, spongy tissue in the middle of the femur, sternum, and pelvis of humans.
How is bone marrow an example of a stem cell niche?
They receive 15% of cardiac output that gives them a big supply of blood carrying oxygen and other amino acids, and therefore contain haematopoietic that produce red red and white platelets each day.
Hair follicles
Pores in the skin that hold hair.
How are hair follicles an example of a stem cell niche?
They have blood capillaries that supply the necessary nutrients that allow them to divide repeatedly to generate the many cells needed for hair growth.
Totipotent Stem cells
- Can differentiate into any cell type, and are found in early-stage animal embryos.
- Useful in regenerative medicine
Pluripotent Stem cells
Able to differentiate into many cell types, but not all.
Multipotent Stem cells
Able to differentiate into several cell types, make up stem cells in adult tissues.
Male gamete size
3 micrometers wide, 50 micrometers long, makes it easier to swim to egg cell
Red blood cell size
- 7 micrometers in diameter, 1-2 micrometers thick
- allows passage through narrow capillaries
- gives large surface area-to-volume ratio so entry and exit o2 is rapid
White blood cell size
B lymphocytes 10-12 micrometers in diameter when inactive, 30 micrometer plasma cells that can produce antibodies in bulk when active.
Female gamete size
- 110 micrometers in diameter
- Large volume of cyt0plasm that allows to hold enough food to sustain the embryo during early stages of development.
Neuron size
- Cell body of 20 micrometers diameter
- Axon extending from nanometers up to meters
- Allows signals to be carried this far
As a cell grows larger, the S.A/Volume ratio…
Decreases
Striated muscle fibers size
- Diameter of 20-100 micrometers, length can exceed 100mm
- Allow them to have large and powerful muscle contractions.
The surface area of a cell affects…
the rate at which materials leave or enter a cell.
The rate at which materials are used or produce depends on..
the volume of a cell
What if a cell becomes too large?
It may not be able to take in or excrete materials quickly enough.
What feature of red blood cells and type 1 pneumocytes give them a big SA/V ratio?
- Flattening makes them very wide and thin, giving them a large area of plasma membrane and a small volume of cytoplasm.
How do proximal convoluted tubule cells in kidney nephrons increase their SA/V ratio?
- They have finger-like projections called microvilli, which reabsorb gluten and other useful substances from the filtrate flowing past them.
How do proximal convoluted cells increase their SA/V ratio (2)?
- Invagination, infolding of plasma membrane to form sacs, folds, or tubules.
- This can be seen through their basal channels that increase the SA for pumping sodium ions out of the cell to generate the Na+ concentration gradient used for glucose co-transport.
Alveoli
Air sacs in the lung where gas exchange happens..
What types of cells make up the wall of the alveolus?
Type I pneumocytes
What makes type I pneumocytes adapted to carry out gas exchange?
They have very little cytoplasm so they are extremely thin and permeable, gases only have to diffuse a very short distance to pass through.
Describe the structure of type II pneumocytes:
- Cube-like cells
- Dense cytoplasm
- Many lamellar bodies (vesicles)
- Make up 5% of alveolus wall but are more numerous
Type II pneumocytes function:
They contain a fluid that is produced and secreted by Exocytosis; allows gases to dissolve as it keeps the inner surface moist, contains the surfactant that reduces surface tension and prevents the sides of the alveoli from collapsing.
How are type II pneumocytes adapts to their function?
- ## Lamellar bodies: specialized vesicles which store phospholipids and proteins produced by rER, and excrete contents by Exocytosis that form the surfactant.
What’s the main function of cardiac muscle cells in the heart?
They pump blood by contracting.
What is the main function of striated muscle?
Attached to the skeleton, it contracts to exert force on a bone in order to maintain or change posture, for locomotion, or for ventilation in the lungs.
What are common adaptions in both skeletal striated and cardiac muscle?
They have contractile myofibrils and large numbers of mitochondria to supply ATP needed for contractions.
Why are male gametes greater in quantity than female gametes?
To increase their chance of fertilization a female gamete.
What are some adaptions of cardiac muscle cells?
- Branched: each is connected to others, allowing electrical stimuli to be propogated rapidly through the tissue.
- Cell-to-cell junctions with intercalated discs and connections between plasma membranes and cytoplasm that allow rapid propagation of electrical stimuli.
- 50-100 micrometers long
- One nucleus per cell
Why are female gametes large in size?
- They contain nearly all food reserves for the early development of the embryo.
What are some adaptions in striated muscle fibers?
- Unbranched, cylindrical shape.
- They are multinucleated but are enclosed in a plasma membrane.
- They have blunt ends where fibres meet bit o intercalated discs or connections.
- Very long, narrow cells, 30,000 micros long an average
Why are female gametes far less greater in quantity than male gametes?
- A large investment in food resources goes to female gametes.
Describe the structure of an egg cell:
Spherical cell, diameter of 110 micrometers
- Corona radiata, follicle cells
- Zona pellucida, membrane
- First polar cell
- Cortical granules
- Cytoplasm, or yolk
- two centrioles
- Haploid nucleus
What are some adaptations of egg cells?
- Haploid nucleus, contains 23 chromos that are passed from mother to offspring.
- Cytoplasm/yolk, contains fat and other nutrients needed for embryo development
- Cortical granules. harden the zona pellucida after fertilization to prevent more than one sperm entering
- Zona pellucida, protects the egg cell and restricts sperm entry
- first polar cell, breaks down as its usually not needed.
- centrioles, organize the mitotic spindle fibers used during mitosis
State the components of a sperm cell’s structure:
- Head (3 micrometers wide, 4 long)
- Plasma membrane
- acrosome
- Haploid nucleus
- Centriole
- Mid-piece
- Helical mitochondria
- Microtubules
- Protein Fibers
State the components of a sperm cell’s structure:
- Head (3 micrometers wide, 4 long)
- Plasma membrane
- acrosome
- Haploid nucleus
- Centriole
- Mid-piece
- Helical mitochondria
- Microtubules
- Protein Fibers
What are some adaptations of the human sperm cell?
- Acrosome: contains enzymes that digest the zona pellusida
- Haploid nucleus: contains 23 chromosomes that are passed on to offspring.
- Helical Mitochondria: produces ATP by aerobic respiration to supply energy for swimming.
- Tail: provides repulsion that allows the sperm to swim to swim up the uterus and oviduct.
- Microtubules: 9 + 2 array that make the sperm tail beat from side to side.
- Protein fibers: strengthens the tail.
