Cytology (Cell physiology) part 4-6 Flashcards by Yuri Diaz

why do cell cells divide?

Growth, regeneration, reproduction

How well did you know this?

Not at all

Perfectly

What type of phase of the cell cycle is this?

_____-cell carrying out daily functions or preparing to divide

Interphase

How well did you know this?

Not at all

Perfectly

What are the types of phases in Interphase?

G1 phase
S phase
G2 phase

How well did you know this?

Not at all

Perfectly

What type of phases of interphase is this?

_______-cell spends 90-95% of its time in this phase growing
and carrying out its everyday functions

G1 phase

How well did you know this?

Not at all

Perfectly

What type of phases of interphase is this?

______-DNA is replicated
• Purpose - before a cell divides it must replicate its DNA so each
daughter cell has a full set of genetic instructions.

S phase

How well did you know this?

Not at all

Perfectly

What type of phases of interphase is this?

______-final “check point”: make sure everything is ready for
mitosis

G2 phase

How well did you know this?

Not at all

Perfectly

What type of phase of the cell cycle is this?

______-division of nucleus producing two nuclei.

M phase (mitosis)

How well did you know this?

Not at all

Perfectly

What type of phase of the cell cycle is this?
________-produces two daughter cells with identical chromosomes.
o Produces most of the cells in the human body (somatic cells).

Mitotic cell division

How well did you know this?

Not at all

Perfectly

What type of phase of the cell cycle is this?
___________-involves two rounds of cell division producing four
daughter cells with unique chromosomes.
o Produces gametes (sperm and ovum) in humans

Meiotic cell division

How well did you know this?

Not at all

Perfectly

What is the structure of DNA?

Double stranded

How well did you know this?

Not at all

Perfectly

In DNA within the double stranded, the chemical side groups of the nitrogen bases form hydrogen bonds, connecting
the two strands (base pairing).
What are they?

A=T Adenine forms two hydrogen bonds with thymine

§ G≡C Guanine forms three hydrogen bonds with cytosine

How well did you know this?

Not at all

Perfectly

In DNA within the double stranded, the Sugar-Phosphate Backbones run antiparallel to each other.
What are some examples?

*Each DNA strand has a 3’ end with a free hydroxyl
group and a 5’ end with a free phosphate group.

*One strand runs 5’ to 3’ and the other runs 3’ to 5’

How well did you know this?

Not at all

Perfectly

In DNA replication, the two parent strands serve as a template for the
synthesis of the new complementary strands. what is the called?

Semi-conservative

How well did you know this?

Not at all

Perfectly

What type of step in DNA replication is this?
_________-Two complementary strands separate,
much like unzipping a zipper.

The 1st step is called initiation of the DNA replication

How well did you know this?

Not at all

Perfectly

Within the first step of DNA replication what occurs here?

_______-DNA sequence where replication begins.
§ There are hundreds or thousands of origin sites per chromosome

Replication Origin

How well did you know this?

Not at all

Perfectly

Within the first step of DNA replication what occurs here?

Strands separate forming a replication “bubble” with __________ at each
end.
§ The replication bubbles elongate and unite as DNA is replicated.

replication forks

How well did you know this?

Not at all

Perfectly

Within the first step of DNA replication what occurs here?

_______-the enzyme that unwinds the double helix and breaks the
hydrogen bonds between complementary base pairs at the replication forks

Helicase

How well did you know this?

Not at all

Perfectly

Within the first step of DNA replication what occurs here?
______-enzyme that constructs an RNA primer complementary to the
DNA template.

Primase

How well did you know this?

Not at all

Perfectly

What type of step in DNA replication is this?
______-Each strand becomes a template along
which a new complementary strand is built.

The 2nd Elongation of DNA replication

How well did you know this?

Not at all

Perfectly

Within the second step of DNA replication what occurs here?
After formation of the RNA primer, ___________ – is the enzyme that
elongates the new strand by adding nucleotides to the 3’end.

DNA polymerase

How well did you know this?

Not at all

Perfectly

Within the second step of DNA replication what occurs here?
Replication always occurs in the 5’ to 3’ direction
* ________ – elongates toward the replication fork, continuous
*________ – elongates away from the replication fork
Ø Okazaki fragments: discontinuous short segments

Leading strand

* Lagging strand

How well did you know this?

Not at all

Perfectly

Within the second step of DNA replication what occurs here?

______-is the enzyme that replaces RNA primers with DNA

DNA polymerase 1

How well did you know this?

Not at all

Perfectly

Within the second step of DNA replication what occurs here?

______-is the enzyme that joins fragments into a single DNA strand

DNA Ligase

How well did you know this?

Not at all

Perfectly

What type of step in DNA replication is this?
_________-Once the two original strands are bound to
their own, finished, complementary strands, DNA replication is stopped, and the two new
identical DNA molecules are complete.

The third step is called termination of the DNA replication

How well did you know this?

Not at all

Perfectly

_______--long threads of DNA wrap around histone proteins. | • Only condensed to form visible chromosomes during mitosis

Chromosomes in Eukaryotes

______-the uncondensed DNA loosely wound around histones during interphase.

Chromatin

How many chromosomes does a human have in total?

46 chromosomes = 23 pairs

what does "n" stance for?

the number of different types of chromosomes | * in humans n =23

``` Human gametes (sperm and ovum) are________.(1n)- meaning each cell has only one set of chromosomes (23 total). ```

Haploid

Somatic humans cells are________ (2n)- meaning each cell has two sets of chromosomes (46 total). § in humans 2n = 46

diploid

_______-are matching pairs of chromosomes | *Humans have 23 pairs (46 chromosomes total).

homologous chromosomes

Part of the autosomes :(autosomal chromosomes) Humans have 22 pair of __________. *These chromosomes have the same genes. o Alleles are different versions of the same gene. o Homologous chromosomes may have identical alleles (meaning the person is homozygous for that gene) or different alleles for the same gene (heterozygous).

autosomes (autosomal chromosomes)

Part of the autosomes :(autosomal chromosomes): Humans also have 1 pair of 21)___________ chromosomes, XY or XX • Two X chromosomes in a female. XY in a male. o The X chromosome has a short region that is homologous with the Y chromosome to enable pairing of chromosomes during mitosis.

sex

Part of the autosomes :(autosomal chromosomes): _______-identical molecules of DNA held together by the centromere in a duplicated chromosome (after DNA replication and before mitosis). o Before a cell divides, it must duplicate its chromosomes so that each new cell gets a complete copy of DNA. o Centromere- region of the chromosome where with a complex of proteins that hold two sister chromatids together.

sister chromatin

What is a gene?

region of the DNA that codes for a portion

Each strand of DNA can contain thousands of _____ | *Each gene has a beginning and an end

genes

DNA is used as the blueprint to direct the production of ______

proteins

Genetic Code in gene; The DNA nucleotide sequence codes for the order in which _______ are put together to form proteins

amino acids

Genetic code in gene Three nucleotides form a 24)________ on the mRNA that codes for a specific amino acid in a polypeptide.

Codon

Genetic code in gene | There are 20 different amino acids but 64 possible ______

codons

Genetic code: | _____-more than one codon for the same amino acid

Some redundancy

In gene ________ is essentially universal in all organisms • Slight variations exist but the majority of the code is universal.

genetic code

________- synthesis of RNA from a DNA template

Transcription

transcription occurs in?

nucleus

Transcription: What type of RNA is this? ______-carries the coded message from the DNA to the ribosome in the cytoplasm

Messenger RNA (mRNA)

Transcription: What type of RNA is this? _______-contributes to the structure of ribosomes that reads the mRNA to synthesize peptides in the process of translation

Ribosomal RNA (rRNA)

Transcription: What type of RNA is this? _______-carries the correct amino acid into the ribosome to be used during translation.

Transfer RNA (tRNA)

What Step of transcription is this? _______-occurs when proteins called transcription factors bind to a DNA sequences called the promoter region (TATA box).

The 1st step Initiation of the transcript.

Within the 1st step Initiation of the transcript. An enzyme called ________-binds to the transcription factors, separates the complementary strands of DNA (breaking hydrogen bonds between base pairs to form a transcription bubble), and catalyzes the formation of a phosphodiester bond (sugar phosphate backbone) between two RNA nucleotides that are complementary to the DNA sequence of transcription start site.

RNA polymerase

What Step of transcription is this? ________-is when RNA nucleotides are added in the 5’ to 3’ direction by RNA polymerase.

The 2nd step called Elogation of the transcription

What Step of transcription is this? ________-occurs when RNA polymerase reaches a termination sequence at the end of the gene. o RNA polymerase releases the DNA and newly synthesized RNA.

The 3rd step is called termination

_________ are use to form mRNA, rRNA, tRNA

Post-transcriptional Modifications

Post-transcriptional Modifications to form mRNA _______-a guanine triphosphate is added that signals for ribosomal attachment in the cytoplasm

5' prime cap

Post-transcriptional Modifications to form mRNA _______-polyA polymerase adds ~250 “A” nucleotides to the end. Protects RNA from being degraded by nucleases.

3' prime poly A tail

Post-transcriptional Modifications to form mRNA _______-introns are cleaved (cut) out by snRNPs (small nuclear Ribonuclear Proteins), and exons are spliced together § Exons – coding region § Introns – noncoding region

Splicing

Post-transcriptional Modifications to form rRNA: rRNA associates with _______ to form two subunits (40s and 60s)

proteins

Post-transcriptional Modifications to form tRNA: Folds into a three dimensional structure (clover shaped) with a three base sequence called an 36)___________that is complementary to a mRNA codon. o 37)____________ of tRNA is when an amino acid is attached to the 3’end.

36) anti-codon | 37) Charging

What step of translation is this? mRNA binds to the 40 small ribosome subunit o The charged tRNA binds to the start codon at the P site of the rRNA. o The arrival of the 60 large ribosome subunit completes the initiator complex.

Initiation is the 1st step of translation

In Initiation is the 1st step of translation mRNA binds to the 42)______ ribosome subunit

40 small

In Initiation is the 1st step of translation The charged tRNA binds to the start codon at the _____ of the rRNA.

P site

In Initiation is the 1st step of translation The arrival of the 43)_______ ribosome subunit completes the initiator complex.

60 large

________-synthesis of polypeptides by ribosomes. § Occurs outside the nucleus in the cytoplasm at free floating ribosomes and ribosomes imbedded in the rough endoplasmic reticulum (RER) § mRNA is read by a ribosome to determine the sequence of amino acids to produce a polypeptide

Translation

rRNA within the ribosome has three tRNA binding sites, what type is this one? ______-site (amino-acyl binding site)

A site

rRNA within the ribosome has three tRNA binding sites, what type is this one? ______-site (peptidyl binding site)

D site

rRNA within the ribosome has three tRNA binding sites, what type is this one? _____-site (growing polypeptide exits the ribosome)

E site

What step of translation is this? The next charged tRNA enters at the A site of the ribosome and the ribosome catalyzes the formation of a peptide bond between the amino acids. o The ribosome then moves down the mRNA. § The tRNA that was at the A site is now at the P site and the empty tRNA that was at the P site now exits at the E site.

Elongation (of the polypeptide chain) is the 2nd step of the translation

What step of translation is this? Elongation continues until a Stop codon is reached (UAA, UAG, UGA) • The polypeptide is then released from the ribosome by a release factor • Polysomes - several ribosomes can simultaneously translate the same mRNA strand to make multiple copies of the same polypeptide

Termination is the 3rd step of the translation

____________ • The start methionine is usually removed • Proteins will undergo folding or modifications o Cleavage into smaller fragments or joined with other polypeptides o Chemical modifications

Post-translational modifications to the polypeptide

Post-translational modifications to the polypeptide what are the chemical modifications? what type is this? _______-addition of carbohydrates

Glycosylation

Post-translational modifications to the polypeptide what are the chemical modifications? what type is this? _______-addition of lipids

Lipation

Post-translational modifications to the polypeptide what are the chemical modifications? what type is this? _______-addition of phosphates

phosphoryglation

What is the definition on Mutation? *Caused by a mistake during DNA replication (rare) or due to environmental factors called mutagens

Changed in the DNA sequence of a gene

What type of mutation is this? _______-change in a single nucleotide * Missense mutations * Silent mutations

Point mutations (Substitutions)

Point mutations (Substitutions) _____________-lead to a different the amino acid during translation. § Example of Sickle Cell Anemia: a point mutation in the gene for hemoglobin leads to an amino acid with a nonpolar R group (valine) instead of the normal amino acid that has a polar R group (glutamate). This change in primary structure changes the tertiary structure of hemoglobin and causes the sickle cell hemoglobin to proteins to clump. The clumping of sickle cell hemoglobin affects erythrocytes leading to the characteristic sickle shaped cells that clump easily and are broken down more rapidly causing anemia

Missense mutations

Point mutations (Substitutions) _______-do not affect the functions of the protein. § There are multiple codons for the same amino acid.

Silent mutations

What type of mutation is this? ______-caused by insertion or deletion of a nucleotide o Changes the reading frame of the codons, usually results in a non-functional protein

Frame-shift mutation

Are all mutations bad?

Although mutations are sometimes harmful….. o They are also the source of the rich diversity of genes in the world They contribute to the process of evolution by natural selection

What phases of mitosis is this? ``` _______- Chromatin condenses into chromosomes • Centrioles migrate to opposite poles, grow microtubules(mitotic spindles) • Nuclear membrane breaks down • Mitotic spindles form ```

Prophase

What phases of mitosis is this? _______- Sister chromatids are aligned in the center of the mitotic spindle

Metaphase

What phases of mitosis is this? _______- Mitotic spindles shorten pulling chromosomes to opposite poles • Sister chromatids separate becoming daughter chromosomes • The cell begins to elongate

Anaphase

What phases of mitosis is this? _______-Chromosomes uncoil into chromatin • Spindle breaks down • Nuclear membrane reforms

Telophase

What phases of mitosis is this? ______-division of the cytoplasm • Original cytoplasmic mass divides resulting in two identical daughter cells.

Cytokinesis

Where do microtubules connect?

Kinetochore

_______ results from uncontrolled cell division. • Cell division is usually under strict control to ensure appropriate proportions. When cell cycle regulation fails, cells start dividing uncontrollably and result in abnormal masses of dividing cells called tumors

Cancer results from uncontrolled cell division

What type of tumors is this? | _______-does not invade adjacent tissues, encapsulated

Benign tumor

What type of tumor is this? ______-invades adjacent tissues o Metastasize – cells break away from primary tumor and travel to other areas of the body

Malignant tumor

What type of factor is this that controls cell division? ______-point in the cell cycle at which the cycle can be signaled to move forward or stopped. o 61)___________ proteins accumulate during the different phases of the cell cycle and stimulate progression past the checkpoints. § Regulate enzymes called Cdks to stimulate progression of the cell cycle.

Checkpoint 61)Cyclin

What type of factor is this that controls cell division? _______-genes that code for proteins that function normally to speed up cell division. o A mutation can convert these genes into 63)______________ that code for abnormally over active proteins speeding up the cell cycle.

Proto- oncogenes 63)Oncogenes

What type of factor is this that controls cell division? ______-code for proteins that function normally to slow down the cell cycle. o A mutation that disrupts the function of these genes can speed up the cell cycle.

Tumor supressor genes

What type of factor is this that controls cell division? | ______-programmed cell death.

Apoptosis

Cytology (Cell physiology) part 4-6 Flashcards

(90 cards)