Cell Structure Flashcards
What are the 3 types of microscopes?
Light, scanning electron and transmission electron
Define magnification
How much bigger the image is compared to the actual size of the object
Define resolution
The smallest distance 2 points can be separated and still seen as separate items
What affects resolving power (resolution)?
Limited by wavelength of light/electrons used by microscope: the shorter the wavelength, the higher the resolution
What is the equation for magnification?
Image size = actual size x magnification
What are the 3 stages of cell fractionation?
Homogenisation, filtration and ultracentrifugation
How big are prokaryotic cells?
0.1-10.0 micrometers
How big are eukaryotic cells?
10-100 micrometers
What organelles do prokaryotic cells have that eukaryotic cells don’t?
May have flagella, plasmids, capsule and pilli
What characteristics do eukaryotic cells have?
Membrane bounds nucleus + organelles. May be unicellular or multicellular. Mitosis for reproduction. DNA associates with his tones (proteins)
What characteristics do prokaryotic cells have?
No membrane bound nucleus or organelles. Always unicellular. Binary fission for reproduction. DNA doesn’t associate with histones
What is the function of the nucleus?
Acts as the control center of the cell through production of mRNA and tRNA + proteinsynthesis
Manufactures rRNA and ribosomes
Retains the genetic material of the cell in the form of DNA and chromosomes
What is the function of mitochondria?
Site of aerobic respiration (link, krebs and oxidative phosphorylation)
Responsible for production of ATP from respiratory substrates such as glucose
What is the role of chloroplasts?
Carries out photosynthesis and harvests sunlight
What are the 2 types of endoplasmic reticulum (ER)?
Smooth ER and rough ER
What is the function of the rough ER?
Ribosomes present
Provides large surface area for synthesis of proteins and glycoproteins
Provides a pathway for transport of materials, especially proteins, throughout the cell
What is the function of the smooth ER?
No ribosomes
Synthesise, store and transport lipids and carbohydrates
What is the function of the golgi apparatus?
Adds carbohydrates to proteins to form glycoproteins
Produces secretory enzymes
Secretes carbohydrates
Transport, modify and store lipids
Forms lysosomes
What is the role of lysosomes?
Hydrolyse material ingested by phagocytic cells
Carries out exocytosis of enzymes in order to destroy material outside of cell
Digest worn out organelles so useful chemicals can be reused
Break down cells once dead (autolysis)
What is the role of ribosomes?
Site of proteinsynthesis
80s in eukaryotic cells
70s in prokaryotic cells, mitochondria and chloroplasts
What is the function of the cell wall?
Provides mechanical strength to prevent cell bursting
Provides mechanical strength to whole plant
Allows water to pass along it and contributes to overall movement of water
What is the function of vacuoles?
Supports herbaceous plants by making cells turgid
Sugars and amino acids act as temporary food store
Pigments may colour petals to attract pollinating insects
What are the stages of cell division?
Interphase, mitosis and cytokinesis
What are the stages of mitosis?
Prophase, metaphase, anaphase and telophase
What are the stages in interphase?
Gap1 (G1): cellular contents excluding chromosomes are duplicated + growth
Synthesis (S): semi-conservative DNA replication, 2x chromatids, 1x chromosomes
Gap2 (G2): checks for errors in DNA replication
What happens in cytokinesis?
Cytoplasm divides into 2
What happens in prophase?
Chromatin condenses into chromosomes
Nuclear envelope and nucleolus breaks down
Centrioles move to opposite poles of cell
Centrioles produce mitotic spindle fibres
What happens in metaphase?
Chromosomes line up on metaphase plate/equator
Spindle fibres attach to centromere of each chromosome
What happen in anaphase?
Spindle fibres contract, pulling identical sister chromatids apart, breaking centromere
What happens in telophase?
Chromosomes decondense back into chromatin
Nuclear envelopes and nucleolus form in both new nuclei
Spindle fibres break down
Pinching of cytoplasm forms cleavage furrow: preparation for cytokinesis
