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Neuro book - bear et al > Chpt 2 > Flashcards

Chpt 2 Flashcards

1
Q

what was discovered in the early nineteenth century that hardened or “fixed” brain tissue

A

-tissues immersed in formaldehyde were hardened, and they discovered a special device called the microtome to make very thin slices

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2
Q

what is histology?

A

The microscopic study of the structure of tissues

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3
Q

describe Nissl stain and clumps

A
  • basic dyes would stain the nuclei of all cells as well as clumps of material surrounding the nuclei of neurons
  • these clumps are called nissl bodies, and the stain is known as the nissl stain
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4
Q

how is the Nissl stain useful?

A

-distinguished between neurons and glia
-enables histologists to study the arrangement or cytoarchitecture of neurons in different parts of the brain

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5
Q

what is Golgi stain

A

-soaking brain tissue in silver chromate solution makes small percentage of neurons darkly coloured in their entirety

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6
Q

what does the golgi stain reveal

A

-neuronal cell body, the region of the neuron around the nucleus that is shown with the Nissl stain, is actually only a small fraction of the total structure of the neuron
-Golgi stain shows neurons have at least 2 distinguishable parts, central region (contains nucleus) and numerous thin tubes that radiate away from the central region

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7
Q

What are neurites?

A

two types: axons and dendrites

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8
Q

what was the opposing ideas of Golgi and Cajal?

A

-Golgi believed cells were fused together to form a continuous reticulum, or network – brain is exception to the cell theory
-Cajal argued neurites of different neurons are not continuous with each other and communicate by contact, not continuity

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9
Q

what is neuron doctrine

A

-the idea that cell theory also applies to neurons

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10
Q

what is the diameter of cell body (soma) of typical neuron

A

about 20 micrometres

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11
Q

what is the cytosol?

A

watery fluid inside the cell, salty, potassium-rich solution that is separated from the outside by neuronal membrane

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12
Q

what are organelles?

A

membrane-enclosed structures (mainly within the soma where there are a number of them)

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13
Q

what is the cytoplasm?

A

everything contained within the confines of the cell membrane, including organelles (nucleus, rough ER, smooth ER, Golgi apparatus, mitochondria), but excluding the nucleus

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14
Q

what is the diameter of the nucleus and what is it contained in?

A

about 5 - 10 micrometres, contained within a double membrane called nuclear envelope (nuclear envelope perforated by pores about 0.1 micrometres across)

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15
Q

where are chromosomes located and what do they contain?

A

-Within the nucleus and contains genetic material DNA (deoxyribonucleic acid)
-each chromosome contains an uninterrupted double-strand braid of DNA, 2 nm wide

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16
Q

Where is the blueprint of your entire body contained?

A

In your DNA

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17
Q

The DNA in each of your neurons is the same, and it is the same as the DNA in the cells of your liver and kidney and other organs, true or false?

A

True

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18
Q

What distinguishes different cells from one another (for example neurons and liver cells)

A

-Specific parts of the DNA that are used to assemble the cell, called genes

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19
Q

if the DNA from the 46 chromosomes were laid out straight, end to end, it would measure…

A

more than 2 m in length

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20
Q

what is the “reading” of the DNA known as?

A

gene expression

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21
Q

what is the final product of gene expression?

A

synthesis of molecules called proteins

22
Q

what is protein synthesis and where does it occur

A

The assembly of protein molecules, occurs in cytoplasm

23
Q

Why must an intermediary carry the genetic message to the sites of protein synthesis in the cytoplasm? And what performs this funcion

A

-Because DNA never leaves the nucleus
-performed by another long molecule called messenger ribonucleic acid (mRNA)

24
Q

what does the mRNA consist of?

A

4 different nucleic acids strung together in various sequences to form a chain

25
Q

what does a sequence of nucleic acids in a chain represent?

A

The information in the gene

26
Q

What is transcription?

A

The process of assembling a piece of mRNA that contains the information of a gene –> the resulting mRNA is called the transcript

27
Q

what is the promoter?

A

The region where the RNA-synthesizing enzyme, RNA polymerase, binds to initiate transcription.

28
Q

What are transcription factors?

A

the binding of the polymerase to the promoter is tightly regulated by other proteins called transcription factors

29
Q

What is the terminator?

A

-aka stop sequence
-other end of the promoter, the RNA polymerase recognises as the end point for transcription

30
Q

what are introns and exons?

A

-introns are additional stretched of DNA within the gene that cannot be used to code for protein
-exons are the coding sequences

31
Q

What is RNA splicing?

A

initial transcripts contain both introns and exons, by RNA splicing, the introns are removes and the remaining exons are fused together

32
Q

What does “alternatively spliced” mean?

A

specific exons are also removed with the introns, leaving an “alternatively spliced” mRNA that actually encodes a different protein –> thus a single gene can ultimately give rise to several different mRNAs and protein products

33
Q

where does mRNA transcripts emerge and where does it travel? And what happens then?

A

-Emerges from the nucleus via pores in the nucleus envelope and travel to the sites of protein synthesis elsewhere in the neuron

-At these sites a protein molecule is assembled much as the mRNA was: by linking together many small molecules into a chain.

34
Q

what are the building blocks of protein?

A

amino acids, 20 different kinds

35
Q

what is translation?

A

assembly of proteins from amino acids under the direction of mRNA

36
Q

What is the “central dogma” of molecular biology?

A

DNA –(transcription)–> mRNA –(Translation)–> Protein

37
Q

what is the human genome?

A

the entire length of the DNA that comprises the genetic information in our chromosomes

38
Q

What is gene copy number variation?

A

-DNA contains missing or duplicated genes
- occurs at the moment of conception

39
Q

what is a single nucleotide polymorphism mutation?

A

-“typographical errors” analogous to a minor misspelling caused by a change in a single letter

40
Q

what is genetic engineering?

A

Ways to change organisms by design with gene mutations or insertions

41
Q

what are knockout mice?

A

one gene has been deleted (or “knocked out”)

42
Q

what are transgenic mice?

A

genes have been introduced and overexpressed; These new genes are called transgenes

43
Q

What are knock-in mice?

A

Native gene is replaced with a modified transgene

44
Q

where does protein synthesis occur?

A

At dense globular structures in the cytoplasm called ribosomes

45
Q

How is protein made at the ribosomes?

A

mRNA transcripts bind to the ribosomes, and the ribosomes translate the instructions contained in the mRNA to assemble a protein molecule – ribosomes use the blueprint provided by the mRNA to manufacture proteins from raw material in the form of amino acids

46
Q

describe the rough endoplasmic reticulum (rough ER)

A

-abounds in neurons
-they are nissl bodies, this is the organelle stained with the dyes that nissl introduced
-major site of protein synthesis because there are many ribosomes in this region

47
Q

what are free ribosomes and polyribosomes?

A

-free ribosomes are free floating ribosomes
-polyribosomes are several free ribosomes that appear to be attached by a thread –> the thread is a single strand of mRNA and the associated ribosomes are working on it to make multiple copes of the same protein

48
Q

what is the difference between proteins synthesized on the rough ER and those synthesized on the free ribosomes?

A

-depends on intended fate of protein molecule
-if its destined to reside within the cytosol of the neuron, then the protein’s mRNA transcript shuns the ribosomes of the rough ER and gravitates toward the free ribosomes
-if the protein is destined to be inserted into the membrane of the cell or an organelle, then it is synthesized on the rough ER

49
Q

describe the smooth endoplasmic reticulum (smooth ER)

A

-stacks of membranous organelles that look like rough ER without the ribosomes
-is heterogeneous and performs different functions in different locations
-some smooth ER is continuous with rough ER and believed to be a site where proteins that jut out from the membrane are carefully folded, giving them their 3D structure
-other types of smooth ER play no direct role in the processing of protein molecules but instead regulate the internal concentration of substances such as calcium

50
Q
A

Neuro book - bear et al (1 decks)

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