chapter 6 - cell division Flashcards
what is interphase
cell preparing for cell division
what happens during interphase
dna is replicated and checked for errors
protein synthesis occurs in cytoplasm
mitochondrai grow and divide in cytoplasm
chloroplasts grow and divide in algal cell cytoplasm
normal metabolic processes occur
what happens during g1 of interphase
proteins which synthesise organelle are produced so organelles replicate. Cell increases in size
what happens during S of interphase
dna is replicated in nucleus
what happens during g2 of interphase
cell continues to increase in size, energy stores are increased and duplicated DNA is checked for errors
what is mitosis
when nucleus divides
what is cytokinesis
when cytoplasm divides and 2 cells are produced
what is g0
when cell leaves the cycle temporarily or permanently
why does g0 happen
-cell becomes specilaised no longer able to divide
-DNA of cell may be damagaed so can no longer divide. Cell becomes senescent
-
what does a high number of senescent cells cause
age-related diseases such as cancer and arthritis
what type of cells can enter g0 can go back to cell cycle
lymphocytes in an immune response
what happens during g1 checkpoint
at the end of g1 phase. Checks for cell size, nutrients, growth factors and DNA damage
what happens during g2 checkpoint
checks for cell size, DNA replication, DNA damage
what happens during spindle assembly checkpoint
checks if chromosomes attach to spindles
what do kinases do
they are enzymes catalysing addition of phosphate group which changes tertiary structure of checkpoint protein activating them during cell cycle
what are checkpoint proteins called
cyclins
what is CDK complex
cyclin- dependent kinase complex
how are tumours formed
cyclin gene may be mutated causing large amount of cyclins to be formed therefore disrupting regulation of cell cycle causing tumour. CDK can be used as chemical inhibitor to treat cancer
is mitosis sexual or asexual
asexual - produce genetically identical offspring
what is mitosis used for
growth , replacement , and repair of tissues, asexual reproduction
what is binary fission
bacteria version of mitosis as they do not have a nucleus
how are chromatids formed
during interphase, each DNA molecule ( chromosomes) is converted to 2 identical DNA molecules, called chromatid
what is the region where 2 chromatids are joined together
centromere
how many chromosomes are there when 2 chromatids are formed from one chromosome
still 1
how are chromatin formed
during interphase, DNA combined with histones to form chromatin
what happens during prophase
chromatin coil and condense to form chromosomes. Nucleolus dissapears
nuclear membrane breaks down
spindles form and attach to centromeres
what happens during metaphase
chromosomes are moved by spindle fibres and aligned at the equator called metaphase plate
what happens during anaphase
centromeres holding pair of chromatids divide and are seperated to opposite poles of cells by spindle fibres
what happens during telophase
chromatids have reached poles are now chromosomes. Nuclear envelope reforms. Chromosome uncoils and nucleolus is formed
cytokinesis begins
what happens during cytokinesis in animal cells
a cleavage burrow forms in middle of cell. Cell surface membrane is pulled inwards by cytoskeleton until it fuses in middle forming 2 cells
what happens during cytokinesis in plant cells
vesicles from golgi apparatus assemble near metaphase plate and vesicles fuse with each other and the cell surface membrane forming new cell wall dividing into 2 new cells
why dont plant cells have cleavage furrow
they have a cell wall so not possible
what happens if dividing cell wall were formed before daughter cells seperated
they would undergo osmotic lysis from surrounding water
what is meiosis
reduction division
what are diploids
2 chromosomes of each type
is meiosis sexual or asexual
sexual
what does meiosis form
gametes as nucleus divides twice to form 4 gametes each with half of the chromosomes number ( haploid)
what are homologous chromosomes
matching set of chromosomes . Each chromosome has same genes at same loci
what are alleles
different version of the same gene
what happens in meiosis 1
homologous chromosomes are seperated into 2 new cells. Each new cell will contain one full set of gene instead of 2 , so cells are haploid
what happens in meiosis 2
- chromatids present in each daughter cell are seperate forming 2 more cells, 4 haploid cells produced in total
what is prophase 1
chromosomes condense
nuclear envelope disintegrates
nucleolus dissapears
spindle formation begins
homologous chromsomes pair up forming bivalents. Chromatids entangle ( crossing over)
what is metaphase 1
homologous chromosomes assemble at metaphase plate
orientation of homologous pair random so maternal or paternal chromosomes can face either pole. This is independent assortment and result in different combinations of alleles.
what is anaphase1
homologous chromosomes are pulled to opposite poles but chromatids stayed joined
sections of DNA on sister chromatids which became entangled break off and rejoin at chiasmata resulting in exchange of DNA
what is telaphase 1
chromosomes assemble at each pole
nuclear membrane reforms
chromosomes uncoil
cellundergoes cytokinesis
dipolid to haploid
what is prophase 2
chromosomes condense
nuclear envelope breaks down
spindle formation begins
what is metaphase 2
individual chromosomes assmeble on metaphase plate
independent assortment occurs again
what is anaphase 2
chromatids of indiviual chromsomes are pulled to oposite poles
what is telophase 2
chromsomes uncoil and form chromatin again
nuclear envelope reforms
nucleolus becomes visible
cytokinesis occurs
what are levels of organistation in multicellular organisms
specialised cells - tissues - organs - organsystems - whole organisms
what is function of erythrocytes
carries oxygen
what is structure of erythrocytes
have flattene bionconcave shape to increase SA: V ration and no nuclei therefore more haemoglobin to carry more oxygen, THey are flexible to squeenze through narrow capilaries
what is role of neutrophils
white blood cell with role in immune system
what is structure of neutrophils
multi-lobed nucleus to squeenze through small gaps to get to sites of infectiom. Granular cytoplasm contains lysosomes that contains enzymes to attack pathogens
what is role of sperms cell
deliver genetic information to female gamete
what is structure of sperm cell
have tail for movement and many mitochondria to supply energy. needed to swim. Acrosome on the head contains digestive enzymes to digest protectivce layers around ovum allowing sperm to penetrate and fertilise
what is role of palisade cells
presnet in mesophyll to absorbs large amounts of light for photosynthesis
structure of palisade cells
contains many chlorophyll, cells are rectangular boxed shapes which can be closely packed to form a continous layer. Thye have thin cell walls increasing rate of diffusion of co2
large vacuole to maintain turgor pressure
chloroplastd can move within cytoplasmt to asborb more light
role of root hair cells
surface of root near growing tips to increase SA by growing root hairto increase SA of cell and maximise. uptake of water and mineral ions
role of guard cells
surface of leaves to form openings called stomata for co2 to enter plant for photosynthesis
waht is structure of guard cells
when they lose water they become less swollen as a result of osmotic fores therefore change shape and close stomata to prevent further water loss
cell wall of guard call is thicker on one side so cell does not change shape symettricllay
what is a tissue
made up of a collection of differentiation cells that have a specific function
what is nervous tissue
adapted to support transmission of electrical impulses
what is epithelial tissue
adapted to cover body surfaces, internal and external
what is muscle tissue
adapted to contract
what is connective tissue
adaptef to hold otbher tissue together or as a transport medium
what is squamous epithelium
made up of specialised squamous epithelial cells to form lining of lungs for rapid diffusion of oxygen into lungs
very thin due to flat cells and is one cell thick
what is ciliated epithelium
made of ciliated epithelial cells
habe cilia that lines trachea to swept mucus away from lungs
contain goblet cells which produce mucus to trap unwanted particles preventing it from reaching alveoli
what is cartilage
connective tissue in ear and noise and end of bones
contains fibre of elastrin and collagen
it is composed of chondrocyte cells in an extracellular matrix.
prevents end of bones from rubbing against each other caysing damage
what is muscle
tissue that contracts to move bones
skeletal muscle fibres contain myofibrils ( dark pink ) which contain contractile proteins
what is epidermis tissue
adapted to cover plant surfaces
what is vascular tissue
adapted for transport of water and nutrients
what is epidermis
single layer of closely packed cells covering surface of plants
covered in waxy , waterproof cuticle to reduce loss of water
contains stomata
allow co2 , o2 and water vapour in and out
what is xylem
vascular tissue
transport of water and mineral ions throughtout plant
composed of vessel elements which are elongated dead cells
walls of these cells are strenghtened with waterproof material called lignin provifing structural support
what is phloem
vascular tissue
transport of organic nutrients from leabes and stems to where it is needed
compose dof columsn on sieve tube cells seperated by perforated walls called sieve plates
what is an organ
collection of tissues adapted to perform particular function in an organism
what is organ system
collection of organs working together to carry out a major function
what is digestive system
breaks down large insoluble molecules into small solbules ones, absorbs nutrients into blood, retains water, removes undigested material from blood
what is cardiovascular system
moves blood around body and provides effective trasnprti system for the substance it carries
what is gaseous exchange system
brings air into body so oxygen can be extracted for respiration and co2 can be expelled
what are stem cells
undifferentiated cells
what are toti-potent cells
stem cells that differentiate into ant type of cells such as extra-embryonic tissues lime umbilicus. can therefore produce whole organisms
what are pluri-potent cells
differentiate into all tissue types but not whole organisms. Present in early embryos
what are multi-potent cells
form a range of cells within a certain type of tissue
where are all blood cells derived from
stem cells in bone marrow
why do red blood cells have short life spans
no nucleus
what are embryonic stem cells
cells present at early stage of embryo development and are totipotent. After 7 days, a mass of cells called blastocytes are fomred and cells are now pluripotent
what are adult stem cells
found throughout life from birth. They are mulitpotent but may be aritificallt triggered to pluripotent cells
can be harvested from unbilical cords
what plant tissue is a source of stem cell
meristematic tissue ( pluripotent)
what are uses of stem cells
-treat heart disease
- treat type 1 diabetes
- treat parkinsons to produce dopamine producing cells
- treat alzheimers
-burns by producing new skin
- drug trials
