Dna structure and replication quiz Flashcards
Interphase
where the cell spends most of its time
Gap 1
Where the cell grows and makes proteins and copies organelles for cell divison
Synthesis phase
Where the cell’s dna is replicated
Gap 2
Cell finishes growing and prepares for mitosis by replicating final organelles and proteins
Mitosis in cell cycle
where the cell divides
- nucleus divides
Cytokinesis in cell cycle
cytoplasm divides
G zero
is a resting phase where cells still do normal functions but are not preparing to divide because they might not be enough resources or the cell itself is securely damaged
Apoptosis
ensures that irregular cells will not divide and that the cell self destructs
What are cancer cells?
Cancer cells can be caused by genetic links, exposer to toxins, redaction, and excess exposer to uv light
- they also divide much faster and take up space form normal cells with damages tissues and organs which can lead to death
tumor
a mass of abnormal cells
Cancer cells Vs Healthy cells
cancer cells secret growth hormones that attract blood vessels and supply the cancer cell with nutrients which takes away those needed nutrients from healthy cells
Parts of a chromosome
chromosomes are made up of a centromere in the center and 2 sister chrmatids
What are chromosomes?
Chromosomes are coils structures made up of DNA and Protiens
- dna wraps around his tones to form chromosomes
Chromatin
grainy material that forms when dna is not coiled into chromosomes
How many chromosomes do humans have?
Humans have 46 chromosomes
- 2 sets of 23 chromosomes/ 1 set from each partner
alleles
alternate form of gene
How do prokaryotic cells do cellular divison
Binary fission which is cells that split into 2 genetically identical cells
steps of cellular divison in prokaryotes
- Dna replication: dna is copied and forms 2 identical chromosomes
- Chromosome segregation: the 2 chromosomes hook onto the cell membrane and move to opposite poles which causes them to seperate
- Seperation: Cell divides by elongating and the cytoplasm divides and forms 2 genetically identical cells
Steps in eukaryotic cell divison
its is more complex that prokaryotic cell divison
- prior to dividing all dna in cells is replicated and organelles are duplicated
1. Prophase= first and longest phase where chromatin condenses into chromosomes and the nuclear membrane breaks down
- centrioles near nucleus seperate and move to opposite sides/ spindle started to form
2. Metaphase= spindle fibers attach to centromere’s of each sister chromatid and line up in the middle of the cell a.k.a (the metaphase plate)
3. Sister chromatids seperate by the short ending of spindle fibers and sister chromatids got to opposite poles
- each polar have a set of chromosomes
4. Telophase= chromosomes uncoil and form chromatin and the spindle break down and new nuclear membrane is formed
5. Cytokinesis= final stage of cell divison in both pro and eukaryotic cells
- in animal cells= cell membrane of parent cell pinches inward along the cell’s equator until 2 daughter cells are formed
- in plant cells= a cell plate forms along the equator of the parent cell and a new cell membrane and cell wall forms along each side of the cell plate
Spindle
consists of microtoublues that pull chromosomes apart during cell divison
What are purines
purines have 2 rings and are adenine and guanine
What are pyramidines
They have 1 ring and are thymine and cytosine
What does a nucleotide monomer consist of?
A sugar (deoxyribose) a phosphate group and a nitrogen containing base
What is a polynucleotide chain
Multiple nucleotide monomers that are the backbone of the double helix
- hydrogen bonds hold the chain together
- 2 hydrogen bonds between adenine and thymine
- 3 hydrogen bonds between guanine and cytosine
DNA’s function
DNA can describe your physical features and contains the genetic information for the cell
Dna theory
Watson and crick classified dna as a twisted ladder and used franklin’s X-ray of dna to build the model of the double helix
Dna replication
occurs in the s phase of the cell cycle
Semi conservative process
half of the parent dna is condensed in each other the 2 daughter cells
- each daughter cell contains 1 strand from parent dna and 1 strand complementary to it
Dna replication enzymes
Helicase: unzips the enzyme
primase: synthesizes new strands and lays down primers- few nucleotides/ primer needs to be placed inoder for enzymes and nucleotides to work
Polymerase: build the new strand and reads exposed bases inside the strand and adds bases inside the strand
Ligase: connect dna fragments
Direction of dna replication in leading strand?
5’ to 3’ end
direction of dna replication in lagging strand
3’ to 5’ end
Dna is antiparalle because?
It never intersects and goes in the opposite direction
Replication fork
Point where the splitting starts and is used as a template to create 2 dna strands that go in the opposite direction
Leading strand
Polymerase adds matching nucleotides onto the template and primer has to happen first so polymerase can hook on to it and build the new dna chain
Polymerase can only copy strands in 5’ to 3’ direction
Lagging strands
copied in a series of segmented
Primase allows polymerase to work backwards in fragments (also know as Okazaki fragments)
Polymerase goes back and replaces rna primers with the dna version
Ligase joins the fragments
What is the proof reader for dna
polymerase proof reads dna and checks for any mutations and errors
Charagaff’s rules
concentration of adenine would always be the same as the concentration of thymine
- 1 ring and 2 rings bond= maintain the shape of the double helix and the distance between the two would be the same
What controls the cell cycle?
Regulatory proteins control the cycle cycle by signaling the cell to either start or delay the next phase of the cycle to ensure that the cell has completed the previous phase
The DNA of a certain organism has guanine as 30% of its bases. What percentage of its bases would be adenine out of 100%?
20%
Because purines make up half of the percentage out of 100
Which enzyme is responsible for adding new free nucleotides to the growing strand?
Dna polymerase
In one strand of DNA the nucleotide sequence is 5’-ATGC-3’. The complementary sequence in the other strand must be
5’-GCAT-3’.
