Bio Flashcards
1
Q
What is the basic unit of life?
A
Cell
All living things are composed of cells, which perform essential functions for survival.
2
Q
What is the function of the cell membrane?
A
Regulates what enters and exits the cell
Comparable to a semi-permeable plastic bag, it helps maintain the cell’s environment.
3
Q
What is cytoplasm?
A
Fluid that fills the cell
It contains various organelles and molecules necessary for cellular functions.
4
Q
What are organelles?
A
Specialized structures within a cell
Each organelle has a unique function, and many are enclosed by membranes.
5
Q
What is the relationship between cell size and organelles?
A
Larger cells require more organelles
This is necessary for the cell to survive and perform its functions.
6
Q
What are the two main groups of cells based on nucleus presence?
A
Eukaryotic and prokaryotic cells
Eukaryotic cells have a nucleus, while prokaryotic cells do not.
7
Q
What does the term ‘eukaryote’ mean?
A
‘True kernel’
This reflects the presence of a nucleus in eukaryotic cells.
8
Q
What is the role of the nucleus in a eukaryotic cell?
A
Control center of the cell
It encloses nearly all genetic material and regulates gene expression.
9
Q
What is the division process for prokaryotic cells?
A
Binary fission
This is a simple reproduction method for prokaryotic cells.
10
Q
What method of division do eukaryotic cells undergo?
A
Mitosis
This process involves the alignment and separation of duplicated chromosomes.
11
Q
What are some examples of membrane-bound organelles in eukaryotic cells?
A
- Mitochondria
- Endoplasmic reticulum
- Golgi bodies
- Lysosomes
These organelles perform specific functions essential for the cell’s life.
12
Q
What are tissues?
A
Groups of similar cells
Tissues work together to perform specific functions in multicellular organisms.
13
Q
How are cells organized in multicellular organisms?
A
Cells → Tissues → Organs → Systems → Organism
This hierarchical organization allows for complex functions and specialization.
14
Q
What is the function of ribosomes in a cell?
A
Involved in synthesizing proteins from amino acids
Ribosomes are numerous, making up about one quarter of the cell and can be mobile or embedded in the rough endoplasmic reticulum.
15
Q
What is the Golgi complex also known as?
A
Golgi apparatus
The Golgi apparatus synthesizes materials such as proteins that are transported out of the cell.
16
Q
What is the primary function of vacuoles in cells?
A
Storage, digestion, and waste removal
Plant cells typically have one large vacuole while animal cells have small, sometimes numerous, vacuoles.
17
Q
Define vesicle.
A
A small organelle within a cell that has a membrane and performs varying functions
Vesicles often move materials within a cell.
18
Q
What are microtubules and their role?
A
Part of the cytoskeleton that helps support the cell and is made of protein
Microtubules are crucial for maintaining cell shape.
19
Q
What is cytosol?
A
The liquid material in the cell, mostly water with some floating molecules
It is a component of the cytoplasm.
20
Q
What does the cell membrane do?
A
Acts as a barrier, keeping cytoplasm in and substances outside out
It determines what is allowed to enter and exit the cell.
21
Q
Fill in the blank: The two types of endoplasmic reticulum are _______ and smooth.
A
rough
22
Q
What are mitochondria responsible for?
A
Generating ATP and involved in cell growth and death
Mitochondria contain their own DNA separate from that in the nucleus.
23
Q
What is the structure of the Golgi apparatus?
A
A series of curved, flattened sacs called cisternae
The cis face receives vesicles containing immature proteins from the RER.
24
Q
What happens to proteins as they move through the Golgi apparatus?
A
They are modified by Golgi enzymes
Modifications can include changes to sugar residues and the addition of sulfate and phosphate groups.
25
What is the function of lysosomes?
Breakdown of various substances
## Footnote
They enclose hydrolytic enzymes active at a low pH and play a role in autophagy.
26
What is autophagy?
The process of recycling nonfunctioning intracellular components
## Footnote
Lysosomes dismantle substrates for recycling.
27
What are the three major components of the cytoskeleton in eukaryotes?
Microfilaments, intermediate fibers, and microtubules
28
True or False: The cytoskeleton is a membraned structure.
False
## Footnote
The cytoskeleton is a membraneless structure found in all cell types.
29
What is the dynamic nature of the cytoskeleton responsible for?
Maintaining or changing cell shape as needed
## Footnote
It provides a 'railway' for motor proteins to direct vesicles.
30
What is the basic function of the plasma membrane?
Cell containment
## Footnote
The plasma membrane also regulates transportation of materials, cell to cell recognition, and cell signaling.
31
What are microfilaments composed of?
Protein molecules called actin
## Footnote
Microfilaments are the thinnest components of the cytoskeleton.
32
During cytokinesis, what structure is formed by microfilaments?
Cleavage furrow
## Footnote
The microfilaments contract to constrict the cytoplasm until the cell pinches into two daughter cells.
33
What is the role of myosin in muscle contraction?
Binds to actin filaments forming myofibrils
## Footnote
Myosin and actin slide past each other as the muscle contracts.
34
What are microtubules primarily made of?
Tubulin
## Footnote
Tubulin is a dimer composed of alpha-tubulin and beta-tubulin.
35
What is the diameter of microtubules?
Around 25 nm
## Footnote
Microtubules are the thickest components of the cytoskeleton.
36
What arrangement do microtubules form?
9 + 2 arrangement
## Footnote
This arrangement is characteristic of cilia and flagella.
37
What is the function of kinesins and dyneins?
Motor proteins that transport vesicles
## Footnote
Kinesins walk toward the plus end, while dyneins walk toward the minus end of microtubules.
38
What are intermediate filaments specialized to withstand?
Tensile forces
## Footnote
They help prevent cell distortion under mechanical stress.
39
What types of proteins make up intermediate filaments?
Over fifty types of proteins
## Footnote
Each type is specific to certain types of cells.
40
What is the role of centrioles in animal cells?
Organize microtubules
## Footnote
Centrioles form a centrosome and help in the formation of the mitotic spindle.
41
What is the structure of centrioles?
Nine triplets of microtubules arranged in a circle
## Footnote
Centrioles are cylindrical structures.
42
True or False: Cilia are typically found in high numbers, while flagella are rare.
True
## Footnote
Cilia are often numerous, while flagella are usually fewer.
43
Fill in the blank: Microtubules can lengthen and shorten by _______ and _______ of the tubulin dimers.
Polymerization; depolymerization
44
What is the primary role of cilia in the respiratory tract?
Sweep mucus out of the lungs
## Footnote
Cilia can also detect signals and transmit information to the cell.
45
What is the main function of the mitotic spindle?
Segregate sister chromatids during mitosis
## Footnote
The spindle fibers extend from centrioles to chromosomes.
46
What is the primary function of the plasma membrane?
It regulates the passage of materials into and out of all types of cells.
## Footnote
The plasma membrane helps maintain the interior conditions of the cell by controlling substance movement.
47
What are phospholipids composed of?
A glycerol backbone, two fatty acid tails, and a phosphate group.
## Footnote
Phospholipids are key components of cell membranes due to their amphipathic nature.
48
Define amphipathic in the context of phospholipids.
Having both hydrophilic (polar) and hydrophobic (nonpolar) components.
49
What is a micelle?
A small spherical structure formed by a single layer of phospholipids with tails pointed inward.
## Footnote
Micelles are important for transporting lipid-soluble materials.
50
What is the role of integral proteins in the plasma membrane?
They facilitate the shuttling of ions and molecules, catalyze reactions, and assist in cell signaling.
## Footnote
Integral proteins can extend completely through the membrane.
51
What are glycoproteins?
Integral proteins with an attached sugar chain that aid in cell recognition.
52
What is osmosis?
The diffusion of water across a semipermeable membrane.
53
What happens to a cell in a hypertonic solution?
Water moves out of the cell, causing it to shrink.
54
Fill in the blank: A solution with a lower solute concentration compared to the cytoplasm is described as _______.
hypotonic.
55
What is the net movement of water during osmosis?
From an area of higher water concentration to lower, or lower solute concentration to higher.
56
What defines an isotonic solution?
It has the same solute concentration as the cytoplasm, resulting in equal rates of water movement in and out of the cell.
57
What are the two main types of transport proteins?
* Channel proteins
* Carrier proteins
58
True or False: Peripheral proteins are tightly bound to the membrane.
False.
59
What is osmotic pressure?
The minimum amount of pressure required to prevent the inward flow of water across a semipermeable membrane.
60
What is osmotic pressure?
Osmotic pressure is determined by the concentration of solute and is calculated using the equation: IT = iMRT
## Footnote
Where: IT = osmotic pressure, i = van 't Hoff factor, M = molar concentration, R = ideal gas constant, and T = temperature in Kelvin.
61
What is passive transport?
Passive transport is the movement of substances across a cell membrane without the input of energy.
## Footnote
It includes processes such as simple diffusion, osmosis, and facilitated diffusion.
62
What are the forms of passive transport?
* Simple diffusion
* Osmosis
* Facilitated diffusion
63
What is osmosis?
Osmosis is the passive transport of water across the membrane.
64
What are aquaporins?
Aquaporins are channel proteins that facilitate the transport of water across cell membranes.
65
What is facilitated diffusion?
Facilitated diffusion is the process where proteins are used to transport substances down their concentration gradients.
66
What is active transport?
Active transport is the movement of solutes into or out of the cell using energy, moving substances against their concentration gradients.
67
What is primary active transport?
Primary active transport involves the pumping of solutes by a carrier protein directly coupled to the hydrolysis of ATP.
68
What is secondary active transport?
Secondary active transport relies on ATP to generate an electrochemical gradient, which drives the active transport of a different solute.
69
What are symport and antiport?
Symport is when both solutes move in the same direction, while antiport is when they move in opposite directions.
70
What are endocytosis and exocytosis?
Endocytosis and exocytosis are types of active transport that use vesicles to import or export substances.
71
What is the difference between endocytosis and exocytosis?
Endocytosis involves the ingestion of materials into the cell, while exocytosis involves the release of materials from the cell.
72
What is pinocytosis?
Pinocytosis is the process of ingesting fluids and is non-specific.
73
What is phagocytosis?
Phagocytosis is the engulfing of particles, sometimes entire cells, by immune system cells.
74
What is receptor-mediated endocytosis?
Receptor-mediated endocytosis is a form of endocytosis that targets specific molecules, such as low-density lipoproteins (LDLs).
75
What are membrane channels?
Membrane channels are transport proteins that form pores for the passage of small, charged particles.
76
What distinguishes ion channels from aquaporins?
Ion channels are usually gated and open or close in response to stimuli, while aquaporins are always open.
77
True or False: Active transport processes require ATP.
True
78
Fill in the blank: _______ is the process where substances move down their concentration gradient without energy input.
[Passive transport]
79
What is the primary function of mitochondria?
Produce most of a cell's ATP
## Footnote
Mitochondria are often referred to as the 'powerhouses' of the cell.
80
What are the two types of endoplasmic reticulum?
Rough ER and Smooth ER
## Footnote
Both consist of continuous membranes called cisternae.
81
What distinguishes rough ER from smooth ER?
Rough ER has ribosomes; Smooth ER does not
## Footnote
Rough ER is involved in protein synthesis, while Smooth ER is involved in lipid synthesis and detoxification.
82
What is synthesized on ribosomes bound to the rough endoplasmic reticulum?
Secretory proteins and plasma membrane-associated proteins
## Footnote
These proteins are synthesized for export or incorporation into the membrane.
83
What is the role of the Golgi apparatus in protein processing?
Modifies and sorts proteins based on their destinations
## Footnote
Proteins are often shipped out of the cell via exocytosis after modification.
84
Fill in the blank: The cisternae of the smooth ER are more _______ in shape than the rough ER.
tubular
85
What is the function of ATP synthase in mitochondria?
Phosphorylate ADP to form ATP
## Footnote
ATP synthase utilizes the proton motive force generated during oxidative phosphorylation.
86
What is the structure of the inner mitochondrial membrane characterized by?
Folds called cristae
## Footnote
The electron transport chain of aerobic respiration is located within these folds.
87
True or False: The outer membrane of mitochondria is a selective barrier.
True
88
What are the primary tasks of smooth endoplasmic reticulum?
Synthesis of lipids, detoxification of drugs, regulation and storage of calcium ions
## Footnote
These functions are particularly important in liver and muscle cells.
89
What happens to proteins that do not fold properly in the rough ER?
They are recycled
## Footnote
Enzymes in the lumen modify proteins to ensure proper conformation.
90
What type of proteins do COPII-coated vesicles transport?
Proteins that fuse with the cis face of the Golgi apparatus
## Footnote
COPII refers to coat protein complex II which is involved in vesicle budding.
91
What is the role of mitochondrial DNA?
Carries 37 genes required for normal mitochondrial function
## Footnote
This DNA is essential for the production of proteins needed in the mitochondria.
92
Fill in the blank: The endoplasmic reticulum constitutes roughly half of all the _______ in a cell.
plasma membrane
93
What is the intermembrane space in mitochondria used for?
Driving chemiosmosis for ATP synthesis
## Footnote
Protons pumped into this space re-enter through ATP synthase, powering ATP production.
94
What initiates the process of apoptosis in mitochondria?
Proteins moving into the cytoplasm in response to oxidative stress
## Footnote
These proteins activate degradation pathways in the cell.
95
What are mitochondria described as due to their ability to replicate their own genome?
Semi-autonomous
## Footnote
Mitochondria can produce many of their own molecules and rely on nuclear genes for others.
96
What theory suggests that mitochondria evolved from free-living prokaryotes?
Endosymbiont theory
## Footnote
This theory posits that mitochondria were once independent bacteria that were engulfed by ancestral host cells.
97
What is the defining structure of eukaryotic cells that contains chromosomes?
Nucleus
## Footnote
The nucleus regulates the DNA of a cell and is responsible for passing on genetic traits.
98
What are chromosomes?
Highly condensed, threadlike rods of DNA
## Footnote
Chromosomes store genetic information about the organism.
99
What consists of DNA and protein that make up chromosomes?
Chromatin
## Footnote
Chromatin is the material that forms chromosomes during cell division.
100
What is the function of the nucleolus?
Produces ribosomal subunits
## Footnote
The nucleolus synthesizes and stores RNA and is involved in protein synthesis.
101
What encloses the structures of the nucleus?
Nuclear envelope
## Footnote
The nuclear envelope consists of inner and outer membranes made of lipids.
102
What are nuclear pores involved in?
Exchange of material between the nucleus and the cytoplasm
## Footnote
These pores regulate the passage of materials including RNA, proteins, and ions.
103
What is nucleoplasm?
The liquid within the nucleus
## Footnote
Nucleoplasm is similar to cytoplasm and contains various substances necessary for nuclear function.
104
What is the role of the nuclear lamina?
Stabilizes the nucleus and regulates events such as DNA replication and cell division
## Footnote
The nuclear lamina is a mesh of protein filaments covering the inner nuclear membrane.
105
What is stored in the nucleus?
Most of a cell's genetic information
## Footnote
DNA is also found in mitochondria and chloroplasts.
106
What is the perinuclear space?
The 20-40 nm gap between the two phospholipid bilayers of the nuclear envelope
## Footnote
This space is where the inner and outer membranes of the nuclear envelope are joined.
107
What kind of channel do nuclear pores form?
Octagonal aqueous channel
## Footnote
Nuclear pores are made of proteins called nucleoporins and allow the transport of molecules.
108
Fill in the blank: The nucleolus disappears early in _______.
mitosis
## Footnote
The nucleolus reappears in the final stage of mitosis (telophase).
109
What is the function of karyopherins?
Transport large molecules like RNA and certain proteins between the nucleus and the cytoplasm
## Footnote
Karyopherins interact with nucleoporins at the nuclear pores.
110
What is the outer membrane of the nuclear envelope continuous with?
Endoplasmic reticulum (ER)
## Footnote
This continuity allows for easy exchange of materials between the nucleus and the ER.
111
What is the largest structure inside the nucleus?
Nucleolus
## Footnote
The nucleolus is responsible for ribosomal RNA synthesis.
112
What are the three regions of the nucleolus?
Fibrillar center (FC), dense fibrillar center (DFC), granular component (GC)
## Footnote
Each region has specific roles in ribosome production.
113
What is the first stage of mitosis?
Prophase
## Footnote
During prophase, chromatin condenses into visible chromosomes, and the nuclear envelope begins to disintegrate.
114
During which phase do chromosomes align along the metaphase plate?
Metaphase
## Footnote
The centrosomes are at opposite poles, and kinetochore fibers assist in lining up the chromosomes.
115
What happens during anaphase?
Sister chromatids are pulled apart towards opposite poles
## Footnote
An enzyme called separin cleaves cohesins, allowing the chromatids to separate.
116
What forms around each set of chromosomes during telophase?
A nuclear membrane
## Footnote
This phase also involves the uncoiling of chromosomes and the reformation of nucleoli.
117
Fill in the blank: The __________ is the imaginary line where chromosomes align during metaphase.
metaphase plate
118
What structures form at the centromere to attach to the spindle fibers?
Kinetochores
## Footnote
These protein-based structures serve as attachment points for kinetochore fibers.
119
True or False: Cytokinesis begins during telophase.
True
## Footnote
Cytokinesis can also begin during late anaphase.
120
What is the longest stage of mitosis?
Prophase
## Footnote
Prophase involves significant changes, including chromatin condensation and nuclear envelope breakdown.
121
What happens to the chromosomes at the end of prophase?
The nuclear envelope has completely dissolved
## Footnote
This allows spindle fibers to interact with chromosomes.
122
What shape do chromosomes take during anaphase as they are pulled apart?
V shape
## Footnote
This occurs as the linear chromosomes bend while being dragged towards the centrosomes.
123
During which phase do the polar fibers overlap and help elongate the cell?
Anaphase
## Footnote
The overlapping polar fibers push away from each other, leading to cell elongation.
124
Fill in the blank: The __________ are the microtubule organizing centers that migrate during prophase.
centrosomes
125
What is the role of motor proteins during metaphase?
Assist in aligning chromosomes
## Footnote
They exert forces to ensure proper chromosome alignment along the metaphase plate.
126
What occurs to the cohesins during metaphase?
They are broken down, except at the centromere
## Footnote
This allows for proper separation of sister chromatids in the next phase.
127
What is cytokinesis?
The process of dividing the cytoplasm to form two daughter cells
## Footnote
It begins during telophase or late anaphase.
128
What happens to the spindle fibers during telophase?
They are depolymerized and disappear
## Footnote
This signifies the end of the mitotic process.
129
What is the first phase of the cell cycle called?
G1 phase
## Footnote
The G1 (first gap) phase begins immediately after cell division.
130
What occurs during the G1 phase of the cell cycle?
Cell volume increases, metabolic activities accelerate, organelles are copied, and enzymes for DNA replication are produced
## Footnote
This phase is often the longest, averaging 6-12 hours.
131
What happens at the G1 checkpoint?
The cell is inspected for growth, nutrients, growth factors, and DNA damage
## Footnote
If it fails, the cell enters the G0 phase.
132
What is the purpose of the S phase in the cell cycle?
DNA replication occurs, doubling genetic content from 2n to 4n
## Footnote
Chromosome number remains at 46, and centrosomes are duplicated.
133
How long does the S phase typically last?
6-8 hours
134
What characterizes the G2 phase of the cell cycle?
Final part of interphase, 3-4 hours of cell growth, continued organelle replication, and protein synthesis
## Footnote
Centrosomes mature as the cell prepares for mitosis.
135
What must happen at the G2 checkpoint?
Inspection for errors in duplicated chromosomes
## Footnote
If errors are found, the cycle is arrested until repairs are made.
136
What two processes make up the M phase of the cell cycle?
Mitosis and cytokinesis
137
What happens during mitosis?
Chromosomes condense, align, segregate, and uncoil
## Footnote
The stages are prophase, metaphase, anaphase, and telophase.
138
What is cytokinesis?
Cytoplasmic division that overlaps with the final stages of mitosis
## Footnote
In animal cells, it involves a contractile ring of actin.
139
What is the average duration of the M phase?
1-2 hours
140
What is growth arrest?
Halting of cell growth in response to internal or external signals
## Footnote
Examples include anchorage dependence and oxidative stress.
141
What is gametogenesis?
The process by which diploid germ cells give rise to haploid gametes
142
How do germ cells differ from somatic cells?
Germ cells can undergo both mitosis and meiosis, somatic cells can only undergo mitosis
143
What occurs during meiosis I?
Homologous pairs exchange DNA and are separated
## Footnote
This results in genetically unique daughter cells with half the chromosome number.
144
What is the outcome of meiosis II?
Results in four haploid cells
145
Fill in the blank: Cells that are significantly and irreparably damaged will either enter a state of _______ or undergo apoptosis.
senescence
146
True or False: The G1 phase is where DNA replication occurs.
False
## Footnote
DNA replication occurs during the S phase.
147
What is the process of producing ova called?
Oogenesis
## Footnote
Oogenesis is the female gametogenesis process, while spermatogenesis refers to the male process.
148
What is the process of producing sperm called?
Spermatogenesis
## Footnote
Spermatogenesis is the male gametogenesis process, while oogenesis refers to the female process.
149
What is restored during fertilization?
Diploid number
## Footnote
Fertilization combines the genetic material from both gametes, restoring the diploid state.
150
What are the two types of reproduction mentioned?
* Asexual Reproduction
* Sexual Reproduction
151
List the stages of Meiosis I.
* Prophase I
* Metaphase I
* Anaphase I
* Telophase I
* Cytokinesis I
152
List the stages of Meiosis II.
* Prophase II
* Metaphase II
* Anaphase II
* Telophase II
* Cytokinesis II
153
What is the length of a sperm cell?
About 0.05 mm
## Footnote
Sperm cells are the smallest human cells.
154
What are the three distinct sections of a sperm cell?
* Head
* Midpiece
* Tail
155
What does the head of a sperm cell contain?
* Centrioles
* Compacted nucleus with tightly coiled DNA
* Acrosome
156
What powers the sliding motion of the microtubules within the tail of the sperm?
ATP produced by mitochondria
## Footnote
The midpiece of the sperm contains the mitochondria.
157
What is the microtubule-based core of the flagellum called?
Axoneme
## Footnote
The axoneme consists of nine doublets of microtubules arranged around a central pair.
158
What happens to the cytoplasm during oocyte meiosis and cytokinesis?
Divides unequally to produce one large viable ovum
## Footnote
This ensures that the ovum has the resources required for the zygote's survival.
159
What does the ooplasm of the egg contain?
* Nutrients for zygote survival
* Molecules needed for protein synthesis
* Organelles (except centrioles)
160
What does each gamete contribute to the zygote?
* 22 autosomes
* 1 sex chromosome
161
What sex chromosome does the egg always contribute?
X chromosome
162
What sex chromosome can the sperm contribute?
Either X or Y chromosome
163
Where does fertilization usually occur?
In the fallopian tube
## Footnote
Fertilization typically happens within 24 hours of ovulation.
164
How many sperm typically reach the secondary oocyte?
Average of 200
165
What is the first step when a sperm makes contact with the oocyte?
Burrows through the corona radiata
166
What happens after the sperm binds to the oocyte?
Plasma membranes of sperm and egg fuse
167
What happens to the cortical granules during fertilization?
Fuse with egg plasma membrane, rendering the vitelline layer impenetrable to sperm
168
What structure is formed when the sperm meets the ovum?
A zygote (fertilized egg) is formed.
169
What is the role of the zona pellucida during fertilization?
It contains proteins that facilitate sperm binding.
170
What happens to the zygote after fertilization?
It develops into a morula and then into a blastocyst.
171
How long does the blastocyst float freely in the uterus before implantation?
Around 3 days.
172
What hormone does the blastocyst secrete to stimulate other hormones?
Human chorionic gonadotropin (hCG).
173
Fill in the blank: The outer cells of the trophoblast fuse to form _______.
syncytiotrophoblasts.
174
What are the three embryonic germ layers formed during gastrulation?
* Ectoderm
* Mesoderm
* Endoderm
175
What is the process called that forms the neural tube from the ectoderm?
Neurulation.
176
When does the heart begin to beat during embryonic development?
Around the third week.
177
What characterizes the fetal stage of development?
Differentiation of reproductive organs, coordinated limb movements, ossification of bones, and increase of subcutaneous fat.
178
True or False: Birth typically occurs around 30 weeks post fertilization.
False
179
What facilitates the transition of the fetus to an extrauterine environment at birth?
Hormones, notably cortisol and catecholamines.
180
Fill in the blank: Epithelial tissues are nourished by diffusion from _______.
capillaries in the underlying connective tissue.
181
What are the three main shapes of epithelial cells?
* Squamous
* Cuboidal
* Columnar
182
Where are stratified squamous epithelial tissues found?
In locations that experience friction, such as the mouth and skin.
183
What is the primary function of connective tissues?
Support and protect the body.
184
What is the nonliving matrix in connective tissues composed of?
* Ground substance (water, proteins, carbohydrates)
* Protein fibers (collagen, elastin, reticular fibers)
185
Fill in the blank: Blood is a connective tissue made of _______.
blood cells and plasma.
186
What type of connective tissue is more flexible than bone?
Cartilage.
187
What is the term for the ability of cells to respond to signals from adjacent cells?
Competence.
188
What are inducers in cell-cell communication?
Cells that secrete signal molecules.
189
What type of signals act on the same cell that secreted them?
Autocrine signals.
190
What is the significance of paracrine signals?
They act on nearby cells.
191
What is reciprocal induction?
Reciprocal induction is a process where signals from one cell type promote differentiation in another cell type.
192
What is cell migration and why is it important?
Cell migration is required for normal embryonic development and occurs during gastrulation and continued development of the embryo.
193
What role do actin filaments play in cell migration?
Actin filaments polymerize to push the cell forward in a crawling motion.
194
What are lamellipodia?
Lamellipodia are flat, sheet-like extensions formed by the rearrangement of the cytoskeleton at the leading edge of a migrating cell.
195
What are the stages of potency in stem cells?
The stages of potency are:
* Totipotent
* Pluripotent
* Multipotent
* Unipotent
196
What is the main difference between totipotent and pluripotent stem cells?
Totipotent cells can develop into any cell type, including placental cells, while pluripotent stem cells can develop into any cell type except placental cells.
197
What is differential gene expression?
Differential gene expression is the mechanism for cell specialization and development of an organism.
198
How do signaling molecules influence gene expression?
Signaling molecules bind to membrane receptors, causing conformational changes that activate transcription factors, which in turn regulate gene expression.
199
What is epigenetic regulation?
Epigenetic regulation involves the methylation of DNA and modification of histone proteins, altering the structure of chromosomes and gene accessibility.
200
What is apoptosis?
Apoptosis is programmed cell death, an important process in embryonic development that eliminates abnormal or misplaced cells.
201
What are caspases?
Caspases are proteases that are activated during apoptosis to cleave specific proteins and initiate cell death.
202
What is senescence?
Senescence is a progressive decline in function due to biological aging and can refer to either an organism or an irreversible state of a cell.
203
What triggers cellular senescence?
Cellular senescence can be triggered by oncogene activation, tumor suppressor gene deactivation, oxidative stress, DNA damage, and telomere shortening.
204
What are telomeres?
Telomeres are repetitive non-coding DNA sequences at the ends of chromosomes that protect coding sequences from degradation.
205
What is the structure of DNA?
DNA is structured as a double helix, resembling a right-handed spiral staircase.
206
Who is credited with the discovery of the double-helix structure of DNA?
Rosalind Elsie Franklin is credited with taking the x-ray diffraction image that aided in the formulation of the double-helix model by Crick and Watson.
207
Fill in the blank: DNA is located primarily in the _______.
nucleus
208
True or False: All DNA in almost all cells is different.
False
209
What is the shape of DNA?
Double helix
## Footnote
DNA resembles a twisted ladder.
210
What are the components of a nucleotide?
Five-carbon sugar, phosphate group, nitrogenous base
## Footnote
The sugar is a pentose.
211
What forms the 'rungs' of the DNA ladder?
Base pairs
## Footnote
Two bases pair up to form the rungs.
212
What makes up the backbone of DNA?
Covalently bonded sugar and phosphate
## Footnote
The backbone is also referred to as the side rails.
213
How are the bases in DNA connected?
Hydrogen bonds
## Footnote
These bonds are easily dismantled for replication.
214
What are the four types of nitrogenous bases in DNA?
* Adenine (A)
* Guanine (G)
* Cytosine (C)
* Thymine (T)
## Footnote
There are about 3 billion bases in human DNA.
215
Which base pairs with thymine (T) in DNA?
Adenine (A)
## Footnote
Cytosine (C) pairs with guanine (G).
216
What are purines and pyrimidines?
Purines: Adenine (A), Guanine (G)
Pyrimidines: Cytosine (C), Thymine (T)
## Footnote
Purines have a two-ring structure; pyrimidines have a single-ring structure.
217
What is a codon?
Group of three nucleotides
## Footnote
Codons code for a single amino acid.
218
How many codons are there, and how many amino acids do they code for?
64 codons, 20 amino acids
## Footnote
More than one codon can code for the same amino acid.
219
What is the start codon?
AUG (methionine)
## Footnote
This codon indicates the beginning of a sequence.
220
What are the stop codons?
* UAA
* UGA
* UAG
## Footnote
These are also known as ochre, opal, and amber, respectively.
221
What initiates DNA replication?
Helicase enzyme
## Footnote
Helicase breaks hydrogen bonds between bases to split strands.
222
What is the origin of replication?
Location where DNA splitting starts
## Footnote
The replication fork is the unwound area of DNA.
223
What is the role of RNA in relation to DNA?
Helper that carries out various functions
## Footnote
Types of RNA include rRNA, tRNA, and mRNA.
224
What is transcription?
Process of copying DNA into RNA
## Footnote
RNA polymerase is the enzyme used in this process.
225
What is translation?
Process by which ribosomes use RNA to assemble proteins
## Footnote
This involves transfer RNA (tRNA).
226
What sugar is found in RNA?
Ribose
## Footnote
DNA contains deoxyribose sugar.
227
What nitrogenous base is found only in RNA?
Uracil (U)
## Footnote
Thymine (T) is found only in DNA.
228
How do RNA and DNA differ structurally?
RNA is single-stranded; DNA is double-stranded
## Footnote
RNA has one backbone, while DNA has two side rails.
229
What role does RNA play in gene expression?
Supports replication and transportation
## Footnote
RNA aids in the expression of genes encoded in DNA.
