Cell Division And Cellular Organisation Flashcards
What is the cell cycle?
The process all multicellular organisms use to grow and divide
What happens in G1 (Gap phase 1) of the cell cycle?
The cell grows and proteins are made
What happens at G1 checkpoint?
The cell checks all the chemicals needed for replication are present
What happens in S (synthesis) stage of the cell cycle?
The cell replicates its DNA
What happens in G2 (Gap phase 2) of the cell cycle?
Cell keeps growing and proteins needed for cell division are made
What happens at G2 checkpoint?
Cell checks whether DNA has been replicated without damage
What happens in the M phase of the cell cycle?
Mitosis (IPMAT) and Cytokenesis
What happens in interphase?
The cell grows and replicated DNA ready for division
What happens in prophase?
The chromosomes condense, and bundles of protein called centrioles move to the end of the cell and spindle fibres are formed. The nuclear envelope also breaks down here.
What happens in metaphase?
Chromosomes line up along the middle of the cell and spindle fibres attach to the centromere.
What happens in anaphase?
Centromeres divide and separate each pair of sister chromatids, pulling them to opposite ends of the cell.
What happens in telpohase?
Chromatids uncoil and become long and thin, making them chromosomes. The nuclear envelopes forms again.
What happens in cytokinesis?
The cytoplasm divides and a cleavage furrow forms to divide the membrane.
What is left (the product) after cytokinesis?
Two genetically identical daughter cells
How can you visualise the stages of mitosis?
Stain the chromosomes and place them under a microscope
What does meiosis produce?
Gametes for sexual reproduction
What happens in meiosis 1?
PMATC just like in mitosis
What happens in meiosis 2?
The two daughter cells undergo P2 M2 A2 T2 and C (PMAT and C) only the new daughter cells only have one chromatid from each chromosome.
What phase does crossing over occur in in meiosis?
Prophase 1
What happens in crossing over?
Chromatids twist around one another and some chromatids swap over, meaning the chromatids contain the same genes but a different combination of alleles
What two events lead to genetic variation in meiosis?
Crossing over and independent assortment of chromosomes
What is the independent assortment of chromosomes?
When homologous pairs line up in M1 and separated in A1, it’s completely random so the four daughter cells have different combinations of maternal and paternal genes
What type of cells are stem cells?
Unspecialised cells
What are unspecialised cells?
They can develop into different types of cells
Where are stem cells found in humans?
Early embryos and bone marrow
What do stem cells in bone marrow differentiate into?
Blood cells (erythrocytes - RBC’s) (neutrophils - WBC’s) to replace worn out blood cells
What do stem cells in the meristem differentiate into?
Xylem vessels and phloem sieve tube elements.
How could stem cells cure Alzheimer’s?
By regrowing healthy nerve cells
How could stem cells cure Parkinson’s?
To regenerate dopamine producing cells.
How are neutrophils adapted to their function?
Their flexible shape allows them to engulf pathogens and the lysosomes in their cytoplasm allies them to digest.
How are erythrocytes adapted to their function?
Their biconcave disc shape provides a large SA for gas exchange and they have no nucleus so there’s more room for haemoglobin.
How are epithelial cells adapted to their functions?
Some are ciliated to move particles away and some are squamous that are thin so there is a short diffusion distance.
How are sperm cells adapted to their function?
Have a flagellum so they can swim to the egg and their acrosome contains digestive enzymes to enable the sperm to penetrate the egg
How are palisade mesophyll cells adapted to their function?
They contain many chloroplasts so they can absorb sunlight and the walls are thin so co2 can easily diffuse into the cell
How are root hair cells adapted to their function?
They have a large surface area for reabsorption and a thin permeable cell wall for entry
How are guard cells adapted to their function?
Thin outer walls and thick inner walls that forces them to bend outwards to open the stomata
What are the three different types of muscle tissue and where are they found?
Smooth - Stomach wall
Cardiac - Heart
Skeletal - Used to move
What is cartilage and where is it found?
A connective tissue in the joints
Name the 4 animal tissues
1) Squamous epithelium
2) Ciliated epithelium
3) Muscle tissue
4) Cartilage
Name the two plant tissues
Xylem and phloem
What does xylem tissue do?
Transports water
What is xylem made up of?
Dead and living parenchyma cells
What does phloem tissue do?
Transports sugars
What is phloem tissue made up of?
Sieve tube elements, companion cells and sieve plates in between the tube
What is an organ?
A group of tissues that work together to perform a particular function
What tissues do the lungs have?
Squamous and ciliated epithelial, elastic connective tissue and vascular tissue
What tissues to leaves have?
Palisade tissue, epidermal tissue, xylem and phloem
What do organs work together to form?
Organ systems
What are the two organ systems?
The respiratory system and the circulatory system
