Cell biology Flashcards by Clodagh cultra

What is the plasma membrane?

-Semipermeable barrier

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What is the role of the plasma membrane?

-Controls traffic between cells and external environment
-Regulated by proteins

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What can diffuse through the plasma membrane?

-Hydrophobic and small neutral molecules

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What cannot diffuse through the plasma membrane?

-Polar &
-Organic ions, molecules and proteins

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What are channel proteins?

-Form a selective pore in the membrane
-Allows specific molecules to pass through

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What are carrier proteins?

-Capture molecules outside the membrane
-Change shape and allows molecules through

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What are pump proteins?

-Act like carrier proteins
-Requires ATP

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What is the plasma membrane made of?

-Phospholipids
-Forms phospholipid bilayer

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What do phospholipids consist of?

-Hydrophobic head
-Hydrophillic tail

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What is the nuclear envelope?

-Porous double membrane
-Separates nucleus from cytoplasm

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What are nuclear pores?

Faciliate and regulate exchange of materials between nucleus and cytoplasm

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What is chromatin in the nucleus surrounded by?

Nucleoplasm

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What are histones?

-Proteins
-Aid the folding of DNA in chromosomes to pack it

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What is chromatin?

-Complex of histones and DNA
-Makes up the chromosomes inside the nucleus

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What is heterochromatin?

-Tightly condensed
-Inactive in transcription

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What is euchromatin?

-Less condensed
-Contains actively transcribed genes

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What is the nucleolus?

-Membraneless part of the nucleus
-Involved in ribosome production and assembly

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What is the cytoskeleton?

-Cellular scaffolding contained within the cytoplasm of all cells

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What are the filaments of a eukaryotic cytoskeleton?

-Microfilaments (actin)
-Intermediate filaments
-Microtubules

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What are microfilaments?

-Concentrated beneath cell membrane
-Composed of 2 intertwined actin chains

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What are the functions of microfilaments?

-Resists tension
-Maintains cell shape
-Cell-to-cell/matric junction

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What are microfilaments important for?

-Cytokinesis
-Muscle contraction
-Cytoplasmic streaming

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What are intermediate filaments?

-More stable (strongly bound)
-Heterogeneous constituents of cytoskeleton

What are the functions of intermediate filaments?

-Maintenace of cell shape
-Organise internal 3D structure of cell
-Anchors organelles
-Structual components of the nuclear lamina

What is the composition of intermediate filaments?

different filaments are: -Made of vimentins: Structural support -Made of keratin: Hair, skin, nails -Neurofilaments: Neural cells -Made of lamin: Structure to nuclear envelope

What are microtubules?

-Made of alpha and beta tubulin -Constantly elongated and shortened -Form a ring around the nucleus -Resist compression

What is the structure of microtubules?

-Protofilaments -Bundle in hollow cylinders -Arranged in imperfect helix -Have polarity

What are the functions of microtubules?

-Intracellular transport -Cytoskeleton of cilia and flagella -Synthesis of plant cell wall -Mitotic spindle

What do microtubules form?

-Centrioles -Cillia -Flagella

What are centrioles?

-Star shaped -Involved in organisation of the mitotic spindle and cytokinesis

What does the position of centrioles determine?

-The position of the nucleus -Crucial role in spatial arrangement of cell organelles

What is ATP synthase?

-Enzyme that synthesises ATP from ADP + Pi -Requires energy from protons (H+) moving down a gradient into the matrix

What is the new theory about the structure of the mitochondria?

-Extensively branched organelles -Fewer -Larger in size -Segments pinch off and fuse with other mitochondria

What is the macromolecule of a sugar called?

Polysaccharide

What is the macromolecule of an amino acid called?

Protein

What is the macromolecule of a nucleotide called?

Nucleic acid

What is the pericardial membrane?

The tissue that surrounds the heart

What does the pericardial membrane consist of?

A layer of flattened epithelial cells supported by connective tissue

What are the 4 components of a cell membrane?

-Cholesterol -Phospholipids -Carbohydrates -Proteins

What does cholesterol and phospholipids from?

-Lipid bilayer -Functions as a selective bilayer

What do phospholipids and carbohydrates form?

Glycolipids

What do carbohydrates and proteins form?

-Glycoproteins

What is the function of glycoproteins and glycolipids?

-Structural stability -Cell recognition -Immune response

What are cells composed of?

-Nucleus -Cytoplasm -Cell membrane -Cytosol -Membrane organelles

What are microvilli and their functions?

-Extensive folding of cell membrane -Increases surface area for absorption

What is the cytosol?

Semi-gelatinous substance

What is the role of the cytosol?

-Contains dissolved nutrients, ions, wastes -Suspends the organelles

What are centrioles and their function?

-Bundles of microtubules -Cause the direct movement of DNA during cell division

What is the golgi apparatus and it's function?

-Hollow membrane sacs -Modifies and packages proteins

What is the nucleus and its function?

-Central lumen with double envelope and nuclear pores -Contains DNA to direct all functions of the cell

What is the nucleolus and its function?

-Region of DNA, RNA and protein -Contains genes that direct synthesis of ribosomal RNA

What is the rough endoplasmic reticulum and its function?

-Membrane tubules continuous with nuclear membrane and edges with ribosomes -Site of protein synthesis

What is smooth endoplasmic reticulum and its function?

-Same as RER without ribosomes -Synthesis of fatty acids and lipids

What are ribosomes and their function?

-Granules of RNA and protein -Assembles amino acids into proteins

What are microtubules and microfilaments and their function?

-Protein fibres -Provide strength and support, enable mobility and transport