Exam 2 Flashcards
Define cytology.
The study of cells
Distinguish among extracellular fluid, interstitial fluid and intracellular fluid.
Extracellular fluid (ECF) is outside of the cells. Interstitial fluid is between the cells, in tissue spaces and intracellular fluid (ICF) is inside the cells.
Describe the composition/charge difference of the ICF compared to the extracellular environment (ECF).
Intercellular fluid has high potassium (k+) inside. Inside is (-) compared to the outside in extracellular fluid, which is (+). It has many (-) charged proteins, fewer positive molecules/ions. Has Cytoskeleton, carbs, lipid storage, inclusions and organelles. Extra
Be able to describe the importance of cell division.
Cells divide to help with growth, development, and tissue repair. Its like a while process called the cell cycle, where the cell gets ready for division and then actually divides into two identical cells. During division, the nucleus divides in a process called mitosis, and then the rest of the cell splits in cytokinesis.
Be able to list the phases of the cell cycle in the proper order.
Interphase: G1 phase, S phase, G2 phase
M (mitotic) phase: mitosis (prophase, metaphase, anaphase telophase, cytokinesis.
Distinguish between interphase and M-phase. List the subdivisions in each (in order).
G1 phase, where the cell grows and carries out its Normal function
S phase, where DNA replication occurs and the cell makes a copy of its genetic material.
G2 phase, where the cell continues to grow and prepares for division.
M-phase, also known as the mitotic phase, is the actual division phase. It consists of two subdivisions:
Mitosis, wich includes prophase, metaphase, anaphase and telophase. During mitosis, the nucleus divides.n
Cytokinesis, where the rest of the cell, such as the cytoplasm and organelles, divides to form two separate cells.
Define mitosis and cytokinesis.
Mitosis: nucleus divides, each daughter cell gets 1 complete set of DNA. Cytokinesis: Cytoplasm with organelles divides.
Describe the events that take place during G1, S and G2 phase.
SO, in a nutshell, G1 is about growth and normal functions, S is about DNA replication, and G2 is about final preparations. It’s all part of the cells journey towards division. Generally, it can range from a few hours to several days.
Describe the process of DNA replication/duplication that occurs in S phase.
During the S phase, DNA replication occurs. Its like the cell making a copy of its genetic material. Imagine it as the cell creating a duplicate of its instruction manual, so it has an extra set of all the important information. This replication process ensure that each new cell formed during division will have a complete set of DNA. Its like having a backup plan for the cells genetic code!
Be able to describe what semi-conservative replication is.
So, semi-conservative replication is a fancy term for the way DNA replicates itself. Its like a clever recycling system! During replication, the DNA molecule splits into two strands, and each strand serves as a template for the creation of a new complementary strand. So, in the end, you have two new DNA molecules, each with one original strand and one newly synthesized strand. Its like keeping half of the old DNA and adding half of the new DNA to create a perfect blend.
Prophase:
this is like the preparation phase. The chromosomes condense and become visible. The nuclear envelope starts to break down, and the spindle fibres begin to form.
Metaphase:
this is where the action happens. The chromosomes line up in the middle of the cell, forming whats called the metaphase plate. The spindle fibres attach to the centromeres of each chromosome. Its like a neat lineup of chromosomes, ready to be divided.
Anaphase:
time for separation. The sister chromatids of each chromosome separate and are pulling towards opposite ends of the cell by the spindle fibres. Its like the chromosomes getting pulled apart.
Telophase:
things start to wind down. The chromosomes reach the opposite ends of the cell and a new nuclear envelope starts forming around each set of chromosomes. Its like the chromosomes finding their new homes and getting cozy
Cytokinesis:
the final act. The cell membrane pinches in, dividing the cytoplasm into two separate cells. Each cell has its own nucleus and complete set of chromosomes. Its like there cell splitting into two, ready to start a new chapter.
Describe the cleavage furrow.
The cleavage furrow is like a little groove that forms during cytokinesis. Its like a tiny indentation that appears in the cell membrane as the cell divides. Picture it as a little pinch or a crease that gradually deepens until the cell separates into two.
DNA
its like the master blueprint of life. DNA carries all the genetic information in our cells. Its made up of a long sequence of nucleotides, which are like the building blocks of DNA
Genes
Think of genes as specific sections of DNA. They contain instruction for making proteins, which are essential for various functions in our bodies. Genes determine our traits and characteristics, like eye colour or height. Each gene has a specific location on a chromosome.
mRNA
mRNA or messenger RNA, is like a courier that carries the genetic instructions from the DNA too the protein-making factories in our cells called ribosomes. Its like a copy of the genes instructions that can easily transported.
Amino acids
these are the building blocks of proteins. There are 20 different types of amino acids, and they links together in a specific sequence dictated by the mRNA. Its like putting a unique sequence of lego blocks to create different proteins.
Proteins
proteins are like the workhorses of our cell. They perform various functions, like enzymes that speed up chemical reactions or structural proteins that give cells their shape. The sequence of amino acids determines the structure and function of the protein.
Be able to discuss how the following are related to one another: DNA, genes, mRNA, amino acids, protein.
n a nutshell, DNA contains genes, genes are transcribed into mRNA, mRNA guide the assembly of amino acids, and amino acids come together to form proteins. Its like a fascinating chain of events that ultimately leads to creation of proteins, which are vital for life.
Transcription
is the process where genetic information from DNA is copied in mRNA. It occurs in the nucleus of eukaryotic cells.
Translation
is the process where mRNA is used as a template to build a protein. It takes place in the ribosomes, which can be found in the cytoplasm of both eukaryotic and prokaryotic cells.
Describe the difference between the states of the DNA of genes that are active (expressed) vs. inactive (not expressed).
Although all cells have the same DNA with the same genes, not all genes are expressed or turned into proteins. The state of DNA is active genes, is open and accessible, allowing transcription factors and RNA polymerase to bind and initiate transcription. In inactive genes, the DNA is tightly packed and inaccessible, preventing gene expression. So, the difference lies in the accessibility of the DNA
Explain how transcription of the template strand is initiated, how the mRNA is elongated, (ie. complementary base pairing) and how transcription is terminated.
So, transcription starts with the promoter, builds the mRNA using complementary base pairing and ends at the terminator. Its like writing out a sentence, with the DNA providing a script.
The cell
Cell theory: based on Robert Hooke’s research
- Cells are the building blocks of all plants and animals.
– All cells come from the division of preexisting cells
– Cells are the smallest units that perform all vital physiological
functions
– Each cell maintains homeostasis at the cellular level
Cytoplasm
intracellular fluid (cytosol) + organelles
Nucleus:
controls cellular activities
Plasma membrane
barrier
Cellular environment
Fluid in compartments: movement between
compartments
Extracellular fluid (ECF)
outside of cells
– Interstitial fluid (between cells, in tissue
spaces)
– Blood plasma, lymph, cerebrospinal fluid
Intracellular fluid (ICF)
inside of cells
– Cytosol with nutrients, ions, proteins, wastes
ICF vs. ECF
• Intracelluar fluid (inside cell)
– High potassium (K+) inside
– Inside (-) compared to outside (+)
• Many (-) charged proteins
• Fewer positive molecules/ions
– Cytoskeleton
– Carbs, lipid storage, inclusions
– Organelles
• Extracellular fluid (outside cell)
– High sodium outside (Na+)
– Extracellular matrix
The nucleus
• Largest organelle (10% total cell volume) with nuclear
membrane, nucleoplasm, nucleolus, pores
• Genetic library of DNA (chromatin, chromosomes):
genes containing genetic code
– Directs synthesis of RNA, proteins
• Control center: cell structure /function
– What, where, when, how much protein made
G1
• G = gap
We will assume preparing to divide:
• Lasts about 8-10hr
• Environmental monitoring
• Cell grows
• Makes new organelles and other
structures for replication
– Starts to copy centrosome so
have 2 pairs centrioles later
– Need them for mitotic spindle
production
S- phase
• DNA synthesis/duplication (~8hr)
• Goal: make another copy of all DNA molecules – need
2 complete sets for 2 identical daughter cells
• Many enzymes involved
• Unwind DNA to separate the DNA strands and copy
DNA replication in S phase
• Two identical DNA
molecules formed
from original DNA
• Semi-conservative
replication: 1 old and
1 new strand/ final
DNA molecule
• New DNA rewinds
around histone
proteins
• Important that new
DNA is not damaged
or broken!
Semi-conservative
replication
1 old and
1 new strand/ final
DNA molecule
G2
• After S phase, before mitosis (~4-6hr)
• Monitoring environment
• Cell growth continues
• Final preparation
• Centrosome replication complete: 2 pairs of
centrioles for mitotic spindle production!
Mitosis
nucleus divides, each daughter
cell gets 1 complete set of DNA!
– Continual process!…0.5 -1.5 hrs
– Stages: PMAT
– Vocab: Chromatin, chromosome,
chromatids
Cytokinesis
Cytoplasm with organelles
divides
– Begins in late anaphase+
DNA
genetic instructions
Gene
segments of DNA code for
RNA→ protein
Overview: From DNA to protein
• DNA directs its own replication -we
saw that during interphase!
• DNA directs protein synthesis (we
will see this now!), but too big to
leave nucleus
• So- mRNA made, carries protein
coding message to cytoplasm
• Protein made in cytoplasm
• DNA: genetic instructions
– Gene: segments of DNA code for
RNA→ protein
• DNA → mRNA (transcription)
– Nucleus
• mRNA → protein (translation)
– Cytoplasm, ribosomes
Inactive genes
DNA supercoiled not
easily accessed
