Module 2: cell communication, genes, genomes Flashcards
three major types of cell surface transmembrane receptors
G protein coupled receptors (GPCRS)
receptors tyrosine kinases (RTKS)
ligand gated ion channels
GPCRS
cell surface transmembrane receptors
- uses G proteins, which binds GTP
- binds ligands
- does not form dimer when activated
-not transmembrane just surface
- neurotransmitters, hormones, yeast mating factors
receptors tyrosine kinases
- has enzymatic function
- forms a dimer when activated
- a transmembrane protein
reacts to the binding of signalling molecules by forming dimers and then adding phosphate groups to tyrosines on the cytoplasmic part of the other monomer making up the dimer,
Ligand gated ion channels
open or close in response to binding by specific signalling molecules, regulating the flow of specific ions across the membrane
second messengers
cyclic AMP( cAMP)
ion ca2
inositol triphosphase IP3
adenylyl cyclase
converts ATP to cAMP
inositol triphosphate IP3
Binds to ip3 gated calcium channels causes the release of calcium ions from the er to the cytoplasm
- produced as a result of the cleavage of pip 2 phospholipid in the plasma membrane
cAMP
widely used secondary messengers
- produced when adenylyl cyclase activates G proteins which converts ATP to cAMP
-phosphodiesterase inactivates cAMP
gap junctions and plasmodesmata
junctions to allow molecules to pass readily between adjacent cells without crossing plasma membrane
paracrine signalling
local signalling that influences cells nearby
endocrine signalling
hormonal, hormones secreted into body fluids usually blood to reach all body cells
stages of cell signalling
signal reception
signal transduction
cellular response
4 types of receptors
GPCR - surface
receptor tyrosine kinases - growth factor
ion channel receptors
intracellulwr receptors
_ bound means Gpcr is inactive
GDP
ligand
signalling molecule
ion channel receptors
a ligand gated ion channel, a type of ion channel receptors acts as a gate that opens when ligand binds to it, allowing or blocking flow of na+ or ca2, extracellular side, important for nervous system, present in er. passive transport because it does not use atp
__ molecules can freely pass through the phospholipid membrane
hydrophobic because if can penetrate he hydrophobic core of the membrane
a ____ is an enzyme that transfers a phosphate groups from ATP to a protein, usually activating that protein ( usually second type of kinase)
protein kinase
____ reverse effect of kinases by removing the phosphate groups testing in the protein returning to inactive form
protein phosphatases
_____ opens, allowing allowing calcium ions to flow out of ER which raises cytosolic ca concentration resulting in a cellular response
IP3
inactivation of ___ causes apoptosis
ced-9
secondary messengers
calcium cAMP and IP3
most widely used secondary messages messenger
calcium
DNA can only be added to ___ in the ____ direction
3’, 5’-3’ direction
DNA POL 1
key role in DNA repair, removes RNA nucleotides of primers from 5’ end and replaces them DNA nucleotides
DNA POL 2
Adds DNA nucleotides to the RNA primer and the continues to add DNA to the growing end of the new DNA strand, uses template strand
-chromatin (loose Dna) condenses into visible chromosomes
nucleoli fisappears
-each chromosomes has two sister chromatids joined at centromere
-nuclear envelop breaks down
-spindle fives start forming from centrioles
prophase
cell grows in preparation for cell division, chromosomes are duplicated, genetic material copied
-g1, s, g2 phase
interphase
prometaphase
-nuclear envelope dissolves, allowing spindle fibres to reach the chromosomes
-spindle fibres attach to the kinetochore(protein structures at the centromeres of the chromosomes)
-chromosomes start moving toward centre of the cell but haven’t lined up yet
-chromosomes lined up in the middle of the cell(along metaphase plate)
-chromosomes at its most dense
-spindle fibres attach to the centromeres of each chromosome
metaphase
-sister chromatids are pulled apart by the spindle fibres towards opposite ends of the sides of the cell
-each chromatids is now considered an individual chromosome
anaphase
-chromosomes decondense back into chromatin
-new nuclear envelope forms around each set of chromosomes
-spindle fibres disappea
telophase
cytoplasms divides creating two identical daughter cells,
in animals cells, cleavage furrow pinches the cell in half in plant cells a cell plate forms between two new nuclei
cytokinesis
G1, s, G2
G1 - cell grows
s - duplication of chromosomes
G2 - chromosomes cannot be seen because they have not yet condensed,
meiosis 1
prophase 1
- spindle formation, nuclear envelope breakdown occur as in mitosis, chromosomes condense progressively
- crossing over occurs
metaphase 1
-pairs of homologous chromosomes are now arranged at metaphase plate
- chromatids are attached to kinetochore microtubules
anaphase 1
- breakdown of proteins responsible for sister chromatids cohesion along chromatid arms allow homologs to separate
telo and cyto 1
- when telo 1 begins, each half of cell has a complete halos set of duplicated chromosomes
What is the main purpose of meiosis?
To produce gametes for sexual reproduction.
True or False: Mitosis results in four genetically identical daughter cells.
False. Mitosis results in two genetically identical daughter cells.
Fill in the blank: During prophase I of meiosis, homologous chromosomes undergo _____ to exchange genetic material.
crossing over
What structure holds sister chromatids together?
Centromere
What is chromatin?
A complex of DNA and proteins that forms chromosomes.
Multiple choice: Which phase of meiosis is characterized by the separation of homologous chromosomes?
Anaphase I
What are centrioles responsible for during cell division?
Organizing the mitotic spindle.
True or False: Asexual reproduction involves the fusion of gametes.
False. Asexual reproduction does not involve gametes.
What is the end result of meiosis II?
Four haploid cells.
During which phase of mitosis do chromosomes align at the cell’s equator?
Metaphase
Fill in the blank: In sexual reproduction, the male gamete is called a _____ and the female gamete is called an _____ .
sperm; egg
What is the difference between chromatids and chromosomes?
Chromatids are replicated chromosomes that are joined together, while chromosomes are the structures that carry genetic information.
Multiple choice: In which stage of meiosis does independent assortment occur?
Metaphase I
True or False: Mitosis is essential for growth and repair in multicellular organisms.
True.
What is the diploid number of chromosomes in humans?
46
Fill in the blank: The process of _____ produces identical cells for asexual reproduction.
mitosis
What is the role of the spindle fibers during cell division?
To separate the chromosomes.
What is the main difference between meiosis and mitosis?
Meiosis results in genetic diversity and haploid cells, while mitosis produces identical diploid cells.
True or False: In meiosis, DNA is replicated before both meiosis I and meiosis II.
True.
What is the significance of crossing over during meiosis?
It increases genetic variation among offspring.
Fill in the blank: The two identical halves of a duplicated chromosome are called _____ .
sister chromatids
What happens during telophase in mitosis?
The chromosomes decondense and the nuclear envelope re-forms.
Multiple choice: Which of the following is a type of asexual reproduction?
Budding
What marks the end of anaphase in meiosis?
The separation of sister chromatids.
True or False: Each parent contributes one allele for a trait in sexual reproduction.
True.
What occurs during metaphase II of meiosis?
Chromosomes line up individually along the equatorial plane.
What is mitosis?
Mitosis is the process of cell division that results in two genetically identical daughter cells.
What is meiosis?
Meiosis is a type of cell division that reduces the chromosome number by half, resulting in four genetically diverse gametes.
True or False: Mitosis occurs in somatic cells.
True
True or False: Meiosis occurs in germ cells.
True
What is the main purpose of mitosis?
The main purpose of mitosis is growth and tissue repair.
What is the main purpose of meiosis?
The main purpose of meiosis is to produce gametes for sexual reproduction.
Fill in the blank: Mitosis consists of ___ phases.
five
Fill in the blank: Meiosis consists of ___ divisions.
two
What is crossing over?
Crossing over is the exchange of genetic material between homologous chromosomes during meiosis.
During which phase of meiosis does crossing over occur?
Crossing over occurs during prophase I of meiosis.
What are the two main stages of meiosis?
Meiosis I and Meiosis II.
How many daughter cells are produced at the end of mitosis?
Two daughter cells.
How many daughter cells are produced at the end of meiosis?
Four daughter cells.
What is a key difference between the genetic composition of the daughter cells in mitosis and meiosis?
Daughter cells from mitosis are genetically identical, while those from meiosis are genetically diverse.
True or False: Mitosis includes homologous chromosome pairing.
False
True or False: Meiosis involves two rounds of division.
True
What is a similarity between mitosis and meiosis?
Both processes involve the replication of DNA before cell division.
What is the result of meiosis in terms of chromosome number?
Meiosis results in gametes with half the original chromosome number.
Fill in the blank: During mitosis, ___ is the phase where chromosomes line up at the cell’s equator.
metaphase
Fill in the blank: During meiosis, ___ is the process that ensures genetic diversity.
crossing over
What happens during telophase in mitosis?
The chromosomes decondense, and the nuclear envelope reforms around each set of chromosomes.
What happens during telophase I in meiosis?
The cell divides into two cells, each with half the number of chromosomes.
How does cytokinesis differ between mitosis and meiosis?
Cytokinesis in mitosis results in two identical cells, while in meiosis, it can result in four non-identical cells after two divisions.
What type of cells are produced by meiosis?
Gametes (sperm and eggs).
What is the role of spindle fibers in mitosis?
Spindle fibers help separate the chromosomes during cell division.
What is the role of spindle fibers in meiosis?
Spindle fibers help separate homologous chromosomes and sister chromatids during the two divisions.
What are autosomes?
Autosomes are chromosomes that are not directly involved in determining the sex of an organism.
Define polyploidy.
Polyploidy is a condition in which an organism has more than two complete sets of chromosomes.
What is an example of an organism that commonly exhibits polyploidy?
Many plants, such as wheat and strawberries, commonly exhibit polyploidy.
What is aneuploidy?
Aneuploidy is the presence of an abnormal number of chromosomes in a cell, either more or fewer than the typical diploid number.
True or False: Alternation of generations is a reproductive cycle that occurs in all organisms.
False
What is meant by ‘alternation of generations’?
Alternation of generations refers to a life cycle that alternates between a multicellular haploid stage and a multicellular diploid stage.
What is sister chromatid cohesion?
Sister chromatid cohesion is the process that keeps sister chromatids together until they are separated during cell division.
Fill in the blank: Chiasmata are the points where __________ occur during meiosis.
crossing over
What is the purpose of chiasmata in meiosis?
Chiasmata facilitate genetic recombination by allowing the exchange of genetic material between homologous chromosomes.
What does synapsis refer to?
Synapsis refers to the pairing of two homologous chromosomes during meiosis.
True or False: Polyploidy can lead to increased genetic diversity.
True
What is the typical number of chromosome sets in diploid organisms?
Two sets of chromosomes.
Name one consequence of aneuploidy.
Aneuploidy can lead to developmental disorders and various syndromes, such as Down syndrome.
What stage of meiosis does sister chromatid cohesion occur?
Sister chromatid cohesion occurs during prophase and metaphase of meiosis.
Fill in the blank: The process of recombination during meiosis is facilitated by __________.
chiasmata
What is the significance of the alternation of generations in plants?
It allows for genetic variation and adaptation through sexual reproduction.
Multiple Choice: Which of the following is NOT a type of polyploidy? A) Autopolyploidy B) Allopolyploidy C) Monoploidy D) Triploidy
C) Monoploidy
What cellular process results in the formation of sister chromatids?
DNA replication during the S phase of the cell cycle.
True or False: Chiasmata form only during mitosis.
False
What is the role of synapsis in genetic diversity?
Synapsis allows for crossing over and recombination, increasing genetic diversity.
Fill in the blank: The process of __________ involves the exchange of genetic material between homologous chromosomes.
crossing over
What is the result of successful synapsis in meiosis?
The formation of tetrads consisting of homologous chromosome pairs.
Multiple Choice: Which of the following conditions is characterized by a complete set of three chromosomes? A) Diploidy B) Triploidy C) Tetraploidy D) Aneuploidy
B) Triploidy
What can lead to aneuploidy during cell division?
Errors in chromosome separation during meiosis or mitosis.
What is independent assortment?
The principle that alleles for different traits segregate independently of one another during gamete formation.
True or False: Independent assortment occurs during meiosis.
True
What phase of meiosis does independent assortment occur?
Metaphase I
Fill in the blank: Independent assortment contributes to genetic _____ in offspring.
diversity
What is crossing over?
The exchange of genetic material between homologous chromosomes during meiosis.
True or False: Crossing over occurs during prophase I of meiosis.
True
What is the significance of crossing over?
It increases genetic variation by producing new combinations of alleles.
Multiple Choice: Which of the following increases genetic diversity? A) Independent assortment B) Crossing over C) Random fertilization D) All of the above
D) All of the above
What is random fertilization?
The process by which any sperm can fertilize any egg, leading to a variety of genetic combinations.
True or False: Random fertilization results in a predictable outcome in genetic variation.
False
Fill in the blank: The combination of independent assortment, crossing over, and random fertilization produces _____ offspring.
genetically unique
What is the role of homologous chromosomes in crossing over?
They exchange segments of DNA during meiosis, leading to genetic recombination.
Multiple Choice: Which process is NOT involved in increasing genetic variation? A) Independent assortment B) Crossing over C) Cloning D) Random fertilization
C) Cloning
What is a tetrad?
A structure formed during prophase I of meiosis, consisting of two homologous chromosomes, each made up of two sister chromatids.
True or False: The outcome of random fertilization is limited to the genetic makeup of the parents.
True
Short Answer: Why is genetic variation important for a population?
It enhances adaptability and survival in changing environments.
Fill in the blank: During meiosis, crossing over occurs between _____ chromatids.
nonsister
What is the result of independent assortment and crossing over combined?
A greater number of genetic combinations in gametes.
True or False: Independent assortment can lead to gametes with the same genetic makeup as the parents.
False
Multiple Choice: Which of the following is a key feature of meiosis? A) DNA replication occurs once B) Chromosomes do not segregate C) Only one round of division D) All of the above
A) DNA replication occurs once
