cell function and structure Flashcards

1
Q

what are the 2 main functions of the cell nuclei?

A

(1) to control chemical reactions within the cytoplasm and

(2) to store information needed for cellular division.

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2
Q

cell nuclei contains what?

A

chromosomes made of DNA.

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3
Q

what is the endoplasmic reticulum?

A

The ER is a site of translation, folding & transport of proteins that become the cell membrane as well as proteins that are to be secreted (exocytosed) from the cell.

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4
Q

what does the endoplasmic reticulum do?

A

ER (endoplasmic “within the cytoplasm”, reticulum “little net”) modifies & makes macromolecules & allows transfer of substances. ER is similar to the plasma membrane.

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5
Q

the endoplasmic reticulum consists of what?

A

The ER consists of an extensive membrane network of tubes & cisternae (sac-like structures) whilst other parts of the ER membrane are continuous.

Parts of the ER are covered with ribosomes. Their rough appearance under electron microscopy led to their being called rough ER (RER), other parts are free of ribosomes and are called smooth ER (SER).

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6
Q

what are Ribosomes?

A

A small, ball-like structure in the cell, made of proteins and RNA molecules, that serves as a platform on which the cell’s proteins are made.

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7
Q

what is the Golgi apparatus?

A

a central delivery system for the cell. It processes proteins targeted to the plasma membrane, lysosomes or endosomes & those that will be secreted from the cell, & sorts them within vesicles.

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8
Q

what are mitochondria and what are its function?

A

A mitochondrion is an organelle sometimes described as “cellular power plants”, because their primary function is to convert organic materials into energy in the form of ATP.

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9
Q

what are Lysosomes and what are their functions?

A

functions:
digest food- used to make energy
clean up and recycle-digest broken organelles

structure: membrane sac of digestive enzymes.

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10
Q

what is cytoplasm?

A

Cytoplasm is a semi-fluid contained inside the plasma membrane. It is composed of ions & soluble macromolecules like enzymes, carbohydrates, salts & proteins.

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11
Q

what is the cytoskeleton and its function?

A

The cytoskeleton is a cellular “scaffolding” or “skeleton” contained within the cytoplasm. It is a dynamic structure that maintains cell shape, enables some cell motion, and plays important roles in both intra-cellular transport and cellular division.

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12
Q

what are the functions of the plasma membrane?

A

All cells have a Plasma Membrane that:

Defines the boundary of the cell

Serves as a selective barrier to the passage of molecules, as mediated by highly selective channel & pump proteins

Receives information/stimuli:
-Enables cells to interact with each other eg. cell signalling

Has capacity for movement and expansion:

  • Imports and exports molecules, which determines the composition of the cytoplasm
  • Distributes membrane lipids to other cell membranes, & to daughter cells when a cell divides
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13
Q

what is the plasma membrane and its function?

A

Phospholipid bilayer depends on its composition
(eg. cholesterol-rich PM is more rigid than ER membrane, which lacks cholesterol)

Lipid bilayer acts as a permeability membrane

Protein molecules mediate other functions

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14
Q

Plasma Membrane-Transport, simple diffusion, facilitation and active transport

A

high concentration into low concentration with no energy input, on energy input but moves from low to high and has energy input

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15
Q

diffusion between a high concentration to low concentration is a?

A

one-way flux

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16
Q

what is Endocytosis and Exocytosis?

A

Molecules/substances may also be taken-up/excreted through the plasma membrane via the formation of a vesicle.

Endocytosis-intake of a substance through the plasma membrane

Exocytosis-release of a substance through the plasma membrane

17
Q

what is Homeostasis?

A

‘Homeostasis refers to the dynamic mechanisms
that detect and respond to deviations in
physiological variables from their “set point” values
by initiating effector responses that restore
the variables to the optimal physiological range’

18
Q

what are some aspects of homeostasis?

A

Homeostasis is a dynamic, not a static, process.

Physiological variables can change dramatically over a 24-hr. period, but the system is still in overall balance.

When homeostasis is maintained, we refer to physiology; when it is not, we refer to pathophysiology.

19
Q

what is a feedback loop?

A

Feedback loops or systems are a common mechanism to control physiological processes.

A positive feedback system (also called a feed forward) enhances the production of the product.

A negative feedback system shuts the system off once the set point has been reached.

20
Q

a strategy to determine homeostasis?

A

Identify the internal physiological variable.

Establish the “set point” value for that variable.

Identify the inputs and outputs affecting the variable.

Examine the balance between the inputs and outputs.

Determine how the body monitors/senses the variable.

Identify effectors that restore the variable to its set point.