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dna/cell cycle/cancer Flashcards

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Biology 101 flashcards
1
Q

term

nucleotides

A

the monomers that make up nucleic acids

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1
Q

term

DNA

A
  • molecule that stores our genetic information
  • makes up our genes, which are on our chromosomes
  • instructions to make proteins in your body
  • instruction book for new cells on how to work properly
  • instructions to make an entire organism
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2
Q

term

nitrogen base

A

part of nucleotide (A, T, G, C)

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3
Q

term

phosphate

A
  • part of nucleotide
  • links nucleotides together
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4
Q

term

deoxyribose

A
  • part of nucleotide
  • links nucleotides together
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5
Q

question

What holds base pairs together?

A

hydrogen bonds

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6
Q

objective

DNA strands are antiparallel to each other. What does that mean?

A
  • each strand has a 5’ end and a 3’ end
  • the two strands run in opposite directions
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7
Q

objective

How is DNA replicated?

A
  1. During DNA replication, both strands of the double helix act as templates for the formation of new DNA molecules.
  2. Copying occurs at a localized region called the replication fork, which is a Y shaped structure where new DNA strands are synthesised by a multi-enzyme complex.
  3. One new strand is leaving at the top of frame and the other new strand is leaving at bottom.
  4. The first step in DNA replication is the separation of the two strands by an enzyme called helicase.
  5. This spins the incoming DNA to unravel it: at ten thousand RPM in the case of bacterial systems.
  6. The separated strands are called three prime and five prime, distinguished by the direction in which their component nucleotides join up. .
  7. The 3’ DNA strand, also known as the leading strand, is diverted to a DNA polymerase and is used as a continuous template for the synthesis of the first daughter DNA helix.
  8. The other half of the DNA double helix, known as the lagging strand, has the opposite 3’ to 5’ orientation and consequently requires a more complicated copying mechanism.
  9. As it emerges from the helicase, the lagging strand is organised into sections called Okazaki fragments.
  10. These are then presented to a second DNA polymerase enzyme in the preferred 5’ to 3’ orientation.
  11. These sections are then effectively synthesised backwards.
  12. When the copying is complete, the finished section is released and the next loop is drawn back for replication. I
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8
Q

term

helicase

A

enzyme that separates strands of DNA

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9
Q

term

DNA polymerase

A
  • an enzyme that binds to the primer during DNA replication and makes a new strand of DNA
  • can only add bases in one directon
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10
Q

objective

What is the difference between a leading strand and a lagging strand in semi-conservative DNA replication?

A
  • one of the new strands, a leading strand, is made continuously, from 5’ to 3’
  • the lagging strand can’t be made continuously because it’s made in the opposite direction, from 3’ to 5’
  • DNA polymerase can only make the lagging strand in a series of small chunks known as Okazaki fragments
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11
Q

question

What do 5’ and 3’ refer to?

A

the carbon atoms on the deoxyribose molecule

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12
Q

objective

What is the importance of cell division to an organism?

A
  • growth of organism (adding more cells)
  • to replace dead/damaged cells (tissue healing and regeneration)
  • stem cells are involved in regenerating and replacing cells throughout the body (blood, bone, skin, muscle, etc.)
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13
Q

objective

What are stem cells and why are they important?

A
  • cells that give rise to all the cells in the body
  • stem cells can divide to create many different types of cells in the body (or to make new stem cells)
  • they are involved in regenerating and replacing cells around the body
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14
Q

objective

Why must cells stay small?

A

to stay efficient

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15
Q

term

chromosome

A
  • coiled up DNA wrapped around proteins called histones
  • 46 of them in the nucleus
  • 23 in nuclei of sex cells
  • DNA is in this form 5% of the time
16
Q

term

chromatin

A
  • uncondensed DNA
  • in this form 95% of the time
17
Q

term

centromere

A

narrow region where sister chromatids connect

18
Q

term

sister chromatids

A
  • identical copies of the chromosome’s DNA
  • two of them make up a duplicated chromosome
19
Q

objective

Describe each stage of the cell cycle.

A

gap1 (11 hrs)
* cell grows bigger and functions normally
* has checkpoints (is the cell big enough? are there enough energy and other reserves? is the DNA damaged?)
gap0
* cell stops dividing
synthesis (8 hrs)
* cell copies DNA
gap2 (4 hrs)
* cell makes more organelles and proteins for division
* has checkpoints (did all our DNA get replicated together? is the DNA damaged?)
mitosis (1 hr)
* cell divides duplicated chromosomes/DNA evenly
* cell divides cytoplasm and organelles (cytokinesis)

20
Q

objective

Describe each stage of mitosis.

A

prophase
* nuclear membrane breaks down
* spindle fibers made of microtubules begin to lengthen as centrioles move apart
* chromatin coils into visible chromosomes

metaphase
* spindle fibers are attached to the centromeres of the chromatids
* chromosomes are pulled to the equator (or middle) of the cell)
* nucleus is gone btw

anaphase
* sister chromatids of duplicated chromosomes are pulled apart as spindle fibers shorten and move to opposite ends of the cell

telophase
* new nucleus forms around each set of chromosomes
* cell membrane pinches inward at center
* chromosomes unwind into chromatin
* spindle fibers break down

cytokinesis
* division of the cytoplasm

21
Q

objective

How is cytokinesis different in animal and plant cells?

A
  • plant cells: cell plate forms (new cell wall)
  • animal cells: cleavage furrow forms (indentation in the cell membrane)
22
Q

term

cleavage furrow

A

indentation in the cell membrane of an animal cell during cytokinesis

23
Q

term

cell plate

A

new cell wall formed during a plant cell’s cytokinesis

24
Q

term

cancer

A
  • uncontrolled growth of abnormal cells
  • shortens the cell cycle and affects gap1 and mitosis the most
  • since the cell cycle is shortened, doctors have to act quickly
25
Q

term

tumor

A

mass of abnormal cells

26
Q

term

benign vs. malignant

A

benign
* confined to one area; slow growing
* stage 0 tumors are benign

malignant
* can spread to other areas; fast growing
* stages I, II, III, and IV tumors are malignant

27
Q

term

metastasis

A

spreading of cancer cells

stage IV tumor is metastastized

28
Q

term

apoptosis

A
  • programmed cell death
  • happens for damaged cells
  • does NOT happen much with cancerous cells
29
Q

question

Why are cancer cells harmful?

A
  • they take nutrients from healthy cells
  • they can’t perform the tasks that healthy cells need to do
  • they crowd out healthy cells
30
Q

term

angiogenesis

A

when cancer cells release chemicals that cause bloood vessels to grow towards the tumor to supply it with nutrients and allow it to metastasize (spread

31
Q

term

mutations

A
  • mistakes in genes
  • can lead to cancer
  • can be caused by radiation (UV and x-rays), chemicals (carcinogens like cigarettes, processed foods and preservatives, and cosmetics and cleaning products), and infectious agents (viruses and bacteria)
  • can also be spontaneous
  • a cell needs multiple mutations for cancer to develop (most have at least 60)
32
Q

question

How does semi-conservative replication help prevent mutations during DNA replication?

A

half of the original molecule is already there to serve as a template for the new strand

33
Q

question

What phase of the cell cycle is most affected by radiation?

A

gap1

34
Q

question

Why would radiation help combat cancer?

A
  • it damages cancer cells
  • interferes with uncontrolled cell division
35
Q

question

What happened during the Hershey Chase experiment?

A

first phase
* phage was produced in a medium that also contained S-35 amino acids
* this led to a phage population with S-35 labeled proteins, but no label in DNA
* phage infected the bacteria by attaching to the outside of the cell and injected the DNA into the cell, but the protein coat stayed on the outside of the cell
* phage in these cells were not radioactive
* when intense shaking occurred, protein coat shook off, but phage production in the cell was unaffected

second phase
* phage were produced in a medium that had P-32 nucleotides
* this led to a population with P-32 labeled nucleotides, but no label in the protein
* when the phage infected the bacteria, radioactive DNA entered the cell and was found in phage that was later produced in the bacteria

bio (8 decks)

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