Chapter 6 Flashcards
What happens during G1?
The cell grows, proteins from which organelles are synthesized are made and organelles replicate
What does the G1 checkpoint check for?
The G1 checkpoint checks for cell size, nutrients, growth factors and DNA damage. If it doesn’t meet these requirements then it will enter a resting state G0
What happens during synthesis
DNA is replicated in the nucleus during synthesis
What does the spindle assembly checkpoint check for
The spindle assembly checkpoint checks chromosomes are attached to the spindle
What happens during G2
The cell growth and proteins needed for cell division are made
What does the G2 checkpoint check for
The G2 checkpoint checks for size, DNA replication and DNA damage
What happens during prophase
First prophase where chromatin fibres condense to form chromosomes and the nuclear envelope breakdown and two centrioles move to opposite poles of the cell and spindle formation begins
What are the stages of mitosis
Prophase, metaphase, anaphase and telophase
What happens during metaphase
During metaphase the chromosomes line up at the centre of the cell
What happens during anaphase
during anaphase the centromeres divide spindle fibres contract separating sister chromatids pulling them to opposite poles of the cell
What happens during telophase
During Tielophase chromatids reach the opposite poles and begin to uncoil and the nucleolus and nuclear envelope reform
What happens during cytokinesis and how does this vary between plants and animals
During cytokinesis the cytoplasm divides in animals and cleavage furrow formed however in plants vesicles assemble at the centre and fused dividing the cell
What is the importance of mitosis in life cycles
Mitosis is responsible for growth replace repair and asexual reproduction
What is the importance of meiosis in life cycles
Meiosis is responsible for producing haploid gametes for sexual reproduction which produces genetic variation
What happens during meosis 1
Prophase 1 the chromosomes condense and homologous chromosomes pair up to form bivalents the nuclear envelope disintegrates and two centrioles move to opposite poles of the cell and spindle formation begins
metaphase 1 the bivalent assemble on the equator with a random orientation which is called independent assortment
anaphase 1 the spindle fibres contract separating the bivalents pulling the homologous pairs to opposite poles
Telophase 1 the homologous chromosomes opposite poles and the nucleus and nucleolus reformed and chromosomes uncoil
Cytokinesis occurs
What happens during meiosis II
prophase 2 chromosomes condense the nuclear envelope breakdown and two centrioles move to opposite poles and spindle formation begins
Metaphase 2 independent assortment occurs as chromosomes assemble on the equator
anaphase 2 spindle fibres contract dividing the centromeres and pulling the chromatids to opposite poles of the cell
Telophase 2 the chromatids uncoil and the nucleolus and nuclear envelope reforms
Cytokinesis occurs
How are cells organised
Specialised cells, tissues ,organs ,organ systems, organism
How are erythrocytes specialised for their function
Erythrocytes are red blood cells they have a biconcave shape which increases surface area to volume ratio for gas exchange no nucleus there is more space for haemoglobin and they are flexible to squeeze through capillaries
How are neutrophils adapted to their function
neutrophils are white blood cells they have a multi lobed nucleus to help them squeeze through gaps to get to infection and many Lysosomes to attack pathogens
How are sperm cells adapted to their function
sperm cells have a flatulent to help them swim they are packed full of mitochondria to provide the energy for something and the acrosome contains digestive enzymes needed to penetrate the egg
How are palisade cells adapted to their function
They have large amounts of chloroplasts for photosynthesis thin walls for a short diffusion path and the large vacuole to maintain turgor pressure
How are root hair cells adapted to their function
they have long hair like projections which increase surface area for absorption extra mitochondria for energy for active transport and thin permeable cell walls
How guard cells adapted to their function
they have a thick inner wall and a thin outer wall so the cell does not change shape symmetrically as volume changes allowing a pore to open up to let water through
How are the squamous adapted to the function
A very thin for efficient diffusion
How are the ciliated epithelial cells adapted to their function
They have hair like structures which beat particles away
Give 6 examples of tissues
Squamous epithilial ciliated epithelial muscle cartilage xylem and phloem
What are stem cells
Stem cells are renewing source of undifferentiated cells that are found in embryos bone marrow and meristems
What can adult stem cells in bone marrow differentiate into
Adult stem cells in bone marrow can differentiate into neutrophils and erythrocytes
What can plant stem cells in meristems differentiate into
Stem cells in meristems can differentiate into xylem and phloem
How could stem cells treat Alzheimer’s
Stem cells can treat Alzheimer’s by regrowing healthy nerve cells to replace the ones that are dying resulting in memory loss
How could stem cells treat Parkinson’s
Transplanted stem cells could regenerate dopamine producing cells which are used to control movement
