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55 Cards in this Set

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Heterochromatin

Tightly packed chromatin, non expressed

Euchromatin

Loosly packed, expressed

Central dogma (crick)

DNA --> RNA --> Protein

Reading frame

The possible points where transcription can begin,


3 possible frames, normally only one is usable

Sequences always start with...

AUG methionine

Ends a sequence

STOP codon

The genetic code is... (5)

- degenerative


- universal


- optimised to minimise effects of mutations


- 3rd postion often doesn't matter


- 1st position change result in similar chemistry

Bacterial dna is... (4)

- Circular


- fairly open structure


- packed by supercoiling + wrapped around proteins


- genes are generally switched on as default

How does RNA polymerase begin transcription?

Sigma subunit binds to its specific promoter region, upstream of template sequence. The sigma unit detaches and the polymerase begins transcribing


Unwinding begins at -10 (where there's lots of A and T) then synthesis starts at +1.

Sense strand

Meaningful sequence, actual code for the peptide chain

Antisense strand

The template strand, used to build rna stand on

Transcription bubble

The area where dna is unwound thfn rewound and rna produced

What proteins and how do they hinder/help transcription

Aplha helix proteins can sit in the major groove. They usually bind to dna in 2 places to specific sequences of 10-12bp.

Histone and nucleosomes

Histone are proteins that help pack dna, it attaches to dna to form nucleosomes, which then form 30nm thick fibres

4 types of atp dependant remodelling

- nucleosome sliding


- removal of nucleosome


- create a remodelled, easily accessible state


- replacement of histones

Methylation

Addition of methyl group (e.g. 5 methyl C)


Promotes tighter packaging


Associated with inactive dna

Acylation

Attachment of a lipids side chain


Promotes opening + gene expression

In bacteria, dna replication is

Bidirectional


Involves 3 polymerases

In eukaryotes ____ and ___ are responsible for division in cytokinesis and ___ for separation of chromosomes. (Opposite in bacteria)

Actin


Myosin


Microtubules

Eukaryotes have ___ origins of ___ , while bacteria have ___

Multiple


Replication


One

MerB is an __ __ and drives ___

Actin homolgue


Segregation of replication origin

FstZ is a ___ ___ and drives ___

Tubulin homologue


Division

Condensin and cohesion proteins

Aid supercoiling of chromatids in mitosis

In plants cell replication there is no ___ ___. Instead a ____ ___ grows across the cell.

Pinching off


New membrane

Cyclins

Proteins whose concentration rise and fall throughout the cell cycle. Points of highest concentration generall indicate boundaries between stages.

Checkpoint

Points in cell cycle where info must be accumulated before progressing to the next stage. Aided by cyclins.

Cyclin dependant kinase (cdk)

In the presence of cyclin, Phosphotylates other proteins signalling progression past check point. Must be active for next stage

P53

Triggers apoptosis if cell is irreversibly damaged.


P53 is damaged or not present in cancerous cells.

Cytokinin

A compound that promotes cell division and inhibits aging in plants

Condensin

The complex pf proteins involved in the compaction of chromosomes onto the proteim scaffold. The bacterial equivalent is SMC in the nucleoid.

Karyotype

The array of chromosomes in an individual. Arranged by length, shape, and centromere location.

Cohesin

Protein complex that regulates separation of chromosomes in mitosis or meiosis

APC

Anaphase promoting complex


Found at spindle checkpoint

MPF

Maturation/Mitosis/Mphase promoting factor



Stimulates mitotic and meitotic phases

The 3 checkpoints

- G1/M (cdc2 / G1 cyclin) Decides whether or not to divide. Damage to DNA, starvation or lack or growth factors can stop replication.



- G2/M (cdc2 / mitotic cyclin) represents commitment to mitosis and assesses success of DNA replication



- Spindle (APC) ensures all chromosomes are attached to spindle in preparation for anaphase

Kinetochore

Disc like proteins at the centromere that function as an attachment sitegor spindle

Septation

Formation of septum (new cell wall and membrane) in binary fission. Facilitated by FtsZ

In the cell cycle, the M Phase consists of ___ (division of the nucleus) and ___ (cell divides intontwo daughter cells)

Mitosis



Cytokinesis

pinocytosis
when a cell takes in liquid (or moves out)
phagocytosis
movement of fragments of organic matter in/out of a cell
lipid rafts

Areas of the plasma membrane that are enriched with cholesterol and sphingolipids.


Contains raft associated proteins.

What is the difference between integral and peripheral membrane proteins

integral - proteins that protrude through the membrane. Often have glycan groups on external regions.


Peripheral - associated with the internal surface of the membrane

The 3 fibres that make up the cytoskeleton

Actin filaments (Microfilaments)


Microtubules


Intermediate filaments

Intermediate filaments are...

the most durable element of the cytoskeleton. They provide structural stability and anchor the cell.


(e.g. keratin, neurofilaments)


Composed of protein tetramers

microtubules are....

largest element with the shortest half life.


Responsible for movement of material in the cell, separation of chromosomes an cytoplasm organisation.


Hollow tubes constructed from 13 protofilaments made up of alpha and beta tubulin (globular protein)

actin filaments are...

Made up of two strands of actin, a globular protein.


They are responsible for cell contraction, movement, extracellular extension formation and pinching off.


Act as anchors for enzymes and ribosomes.


Concentrated below the plasma membrane.

4 components required for moving materials in cells

1) Vesicle or organelle to be transported


2) Motor proteins that provide energy driven motion


3) a connector molecule to connect the vesicle to the motor molecule


4) microtubules on which vesicles can move like a train track

the two motor proteins

Kynesin - uses ATP to move vesicles to the cell periphery (to the positive end of actin)


Dynein - to the inside (to the -ve end)

cells crawl by ____ ___ of ___ at the leading edge which is then stabilised by _____. Forward movement is achieved though action of the protein ____.

rapid polymerisation of actin


microtubules


myosin

eukaryotic flagella have a _____ structure. Cilia are similar but ___



9+2


shorter

animal cells excrete an _____ ____ which is made of and elaborate mixture of _____

extracellular matrix (ECM)


glycoproteins

the centrosome is known as the ____ ____ ___ and is the ___ ____, often found surrounding a pair of ____. Plants and fungi lack ___ but still have ___

microtubule organising centre


pericentriolar material


centrioles


centrioles


centrosomes

Chaperone proteins....
help other proteins fold correctly, are found in virtually every studied organism and increase in number when cells are exposed to high temperatures.
Domains
A functionally distinct part of a proteins tertiary structure
motifs
How elements of a proteins secondary structure interact and fold. (e.g. helix-turn-helix or β-α-β motifs)