Cells Flashcards
Function: cell membrane
Controls what enters and leave the cell
Function: nucleus
Control centre of the cell - control is mediated by DNA
Function: nucleolous
Manufactures ribosomes
Function: mitochondrion
Site of aerobic respiration
Function: smooth ER
Manufactures steroids and cholesterol
Function: Rough ER
Site of protein synthesis
Function: Golgi apparatus
Sorts, packages and modifies proteins for export
Function: lysozyme
Contains enzymes for intracellular digestion
Function: ribosome
Site of translation
What does a tight junction do?
- intimate association between membranes of adjacent cells
- prevents substances from passing between cells and forces them to pass through cell membrane
What do desmosomes do?
- strong and large contact point between two cells)
- intermediate filaments provide strength
What do gap junctions do?
- channels connecting cytoplasm of two cells made up of proteins called connexons
- allow ions and small molecules to pass between adjacent cellls
What are the different types of cell junctions?
- tight junctions
- desmosomes
- gap junctions
What are the stages of the cell cycle?
- G1 (first gap phase)
- S phase (synthesis)
- G2 phase
- M (mitotic) phase
What is G0 phase?
When a cell leaves the cell cycle and ceases to divide for days, years of the rest of its life
What occurs during G1 phase?
Growth and normal metabolic roles
What occurs during S phase?
DNA replication
What occurs during G2 phase?
Growth and preparation for mitosis.
What are the main functions of mitosis?
Growth and regeneration/repair of body tissues
What occurs during prophase?
- chromosomes condense
- nuclear envelope breaks down
- spindle fibres grow from centrioles
- centrioles migrate to opposite poles of the cell
What occurs during metaphase?
- chromosomes lie along cell midline
- some spindle fibres attach to kinetochores
- fibres of aster attach to plasma membrane
What occurs during anaphase?
- centromeres divide into two
- spindle fibres pull sister chromatids to opposite poles
- each pole now has an identical set of genes
What occurs during telophase?
- chromosomes gather at each pole of the cell
- chromatin decondenses
- new nuclear envelope appears at each pole
- new nucleoli forms in each nuclei
- mitotic spindle breaks down
- cytokinesis occurs and the cytoplasm splits into two
Function: centriole
Forms spindle during cell division
What occurs during G2 phase?
- DNA checked for errors
- cell grows and produces organelles for mitosis
What is the diameter of a mitochondrion?
0.5-1.0 micrometers
What make up the cytoskeleton?
Proteins that have a structural role within the cell
What are the types of proteins that make up the cytoskeleton?
- microfilaments
- intermediate filaments
- microtubules
Microfilaments
- thinnest
- made of actin
- 2nm wide
- outer shell of the cell - gives peripheral support to the cell, pinches cell during cytokinesis
Intermediate filaments
- 10nm wide
- form networks that can transverse the cell
- particularly important for cell junctions
Mircotubules
- important for transport
- made of tubulin
- are a part of the spindle in mitosis
- 25nm wide
How long are each phases of the cell cycle?
8-10
6-8
4-6
1-3
Microvilli
- increase the surface area of a cell
- commonly involved in absorption
- microfilaments for rigidity
- 90nm in diameter
Cilia
- used for moving material along cell membrane
- microtubules for strength (9 pairs)
- attached to a basal body inside the cell
- 250nm in diameter
What are spindle fibres made of?
Microtubules
