Multi Celluar Flashcards
What are some opinions on Multicellular Organisms ?
individual cells tend to lose the ability to survive on their own in conditions the organism can survive
- the organism can lose the ability to survive even if only a tiny percentage of its cells stop working
Examples of Multicellular and unicellular organism ?
Unicellular organism
- Amoeba
- Bacteria
Multicellular Organism :
- Plants
- Humans
- Animals
Unicellular: organisms made by only one cell Multicellular: organisms made by more than one cell.
Animals and plants generally originate from a single cell, the “zygote
What do Multicelluar need to do ?
Divide… but stay attached
Specialise and integrate Know where they are and where to go,
know what to do and when to stop => communicate and control what they do
Reproduce differently from unicellular organisms
Function of Somatic cells
Somatic cells share the genomic sequence
During mitosis, a somatic cell duplicates its DNA and divides, creating two identical cells. One stays a stem cells and the other differentiates into the type of cell that is needed. Somatic cells are found in niches in different organs tissue. They need to be activated in order to start dividing
Every cell in your body has the same genome (same DNA sequence).
Somatic cells differ in the transcriptomic sequence and proteomic sequence
Red Blood cells specifically express haemoglobin; Myosin for Muscle cells and insulin for pancreatic cells. All these cell type express actin.
Porkaryotes and Eukaryotes
In prokaryotic cells, genes can be switched off by repressor proteins
ligand-dependent DNA-binding proteins can turn transcription on or off
In eukaryotes the gene control region consists in a promoter plus many cis-regulatory sequences
As for the prokaryotic cells, repressors and activators can turn transcription on or off in eukaryotes
Coupling eukaryotic gene expression changes to extracellular signals
Control of Gene expression
Differentiated cell types differ in their patterns of protein expression
Much of this is under transcriptional control
Both eukaryotic and prokaryotic cells use sequence-specific DNAbinding proteins to control gene transcription
DNA does not need to be unwound/dissociated to accomplish this
DNA-binding proteins may activate or inactivate their target genes
In multicellular organisms, many aspects of transcriptional regulation are regulated by environmental signals
What is Mitosis ? Concept of the Cell cycle ?
The process where a single cell divides resulting in generally two identical cells, each containing the same number of chromosomes and genetic content as that of the original cell.
How many phases in Eukary?
four
G1 - Between M/s phase
G2 - S an mitosis
G1, S , G2 AND M which is known as interphase
Extracelluar conditions ?
IF the extraceullar condictions are unfavourable , cells delay progress through G1 and may enter restinsg state G0 for days and weeks
IF the conditions are favourable, signals grow and divide are present , cells in early G1 or G0 Progress through near end of G1 known as start
After this its commited to DNA replications even if the extracelluar signals stimulate cell growth and division are removed .
Stages of Mitotic Cell cycle ?
- G1 - cell grows with 2n DNA content and accumulate enough precursors to proceed to cell division
S - A second copy of all DNA is synthesised - 4n
G2 - Cells no has double the DNA content ( 4n) prepares for cell division
M - Cell segregates the two replicas of each chromosomes to opposite poles of the cell then divides
Daughter cells 2 n ten returns to G1 or enter a quesent zone G 0
Interphase occurs in all stages accept M
Key steps in Mitosis (Prophase)
Prophase
- Nuclear envelopes dissolves
- Centrosomes move to the opposite pole
- Mitotic spindle assembles between the two centrosomes
- Chromosomes (each with two sister chromatids ) begi to condense
Key steps in Mitosis ( Prometaphase)
Breakdown of nuclear envelope
Chromosomes can attach to the mitotic spindle kinetochore and undergo active movements
Key steps in Mitosis ( Metaphase)
One sister chromatid of each chromosomes attached to one centrosome , other side sister chromatid to other
Chromosomes are maximally condensed and alingned to cell equator
Key steps in Mitosis ( Anaphase)
Two sister chromatids of all chromosomes become separated , each mitigating to opposite poles and ensuring that each pole accumulates one sister chromatids from each other the original 2n Chromosomes
Key steps in Telephase
Two sets of daughter chromosomes arrive at the poles of spindle and decondense
New nuclear envelope reassembles around each other set completing formation of two nuceli
Two nuclear envelopes begin to form telophase .
