Biology Unit 4 Flashcards
Genetics is a branch of biology that studies
genetic materials of organisms and how traits are passed from one generation to the next through genes
The genetic material of an organism is a material
That Carries genetic information and passes it from one generation to the next generation to perpetuate life
The genetic material in almost all organisms is_____and ______ is also a genetic material in some viruses like HIV, COVID -19
-DNA
-RNA
What is DNA ?
It’s the hereditary material in humans and other organisms. It exists in a double helix formed by base pairs attached to a sugar-phosphate backbone.
_____________are the basic building blocks of a DNA molecule
Nucleotides
Each nucleotide is composed of ? For RNA and DNA
Sugar
DNA- deoxyribose
RNA- ribose
Phosphate group - the same
Nitrogenous base
DNA - Adenine, Thymine , Guanine and Cytosine
RNA - Adenine, uracil , Guanine and Cytosine
The nitrogen bases belong to the two large chemical families called
- purine
- pyramidine
Ñame the two nitrogenous bases that are purine
- Guanine
- Adenine
Ñame the nitrogenous bases that are pyrimidines
- cytosine
- thymine
- uracil
What is the difference between purines and pyrimidines
Purines are two ringed while pyrimidines are single ringed
Purines are nine membered double rings while pyrimidines are six membered single rings
Purines are heterocyclic nitrogenous compounds while pyrimidines are just nitrogenous compounds
Who discovered the double helix structure of a DNA molecule
James Watson and Francis Crick
The nitrogenous bases form _________bonds to form ladder like structure
Hydrogen
Do the two strands of DNA run in opposite directions or in the same directions
They run in opposite directions
They show polarity (two ends are different)
The one is referred as 5’ end and the other is 3’ end.
Guanine pairs up with
Adenine pairs up with
- cytosine
- thymine , uracil
What are genes
Sections of the DNA structure that contain the set of instructions that determine the characteristics of an organism
Genes are found on ? They are transferred from parent to offspring through?
- chromosomes
- transferred durning cell division ( for both sexual and asexual)
What are chromosomes
are threadlike structures made of a protein called histone and DNA molecule
How is a gene arrangements in a DNA and where is it found
-it’s arranged linearly along the length of each chromosome (like beads on a string)
- it’s found in its own unique position locus or loci( plural)
RNAs are made from DNA in the process of
Transcription
What does DNA replication is semi conservative mean
It means that each strand acts as a template for the synthesis of a new strand. As a result ,Each new DNA molecule is a combination of one old and one new strand
What does DNA replication is semi conservative mean
It means that each strand acts as a template for the synthesis of a new strand. As a result ,Each new DNA molecule is a combination of one old and one new strand
DNA polymerase
- it adds new nucleotides and links them together in the correct sequence using the template DNA strand
- it adds nucleotides to the deoxyribose(3’) ended strand in a 5’ and 3’ direction
RNA primase
Synthesizes RNA primers complementary to the DNA strand
DNA ligase
Glues two fragments of DNA together by a phosphodiester bond
Topoismerase
Prevents super coiling at the region ahead of replication fork
What is replication fork
Is the point between newly separated strands and non separated strand
What is leading and lagging strand
Leading - is the new strand of DNA that is synesized in the Same direction as the growing replication fork
Lagging -is the new strand of DNA that is synesized in the opposite direction as the growing replication fork
What is leading and lagging strand
Leading - is the new strand of DNA that is synesized in the Same direction as the growing replication fork
Lagging -is the new strand of DNA that is synesized in the opposite direction as the growing replication fork
What are the steps of DNA replication
Stage one - the DNA is unwinded
Stage two - New strands are made
Stage three - twist to form a double helix
_______ is a Stage of interphase where the cells are quite active at a biochemical level
G1 ( the first gap )
At the g1 stage it prepares itself for DNA replication by accumulating
- the building blocks of chromosomal DNA
- the associated proteins with DNA replication
- sufficient energy reserves to complete the task
What happens durning the s phase
- it forms identical pairs of DNA molecules ( sister chromatids)
- the Centro some duplicate and centrioles develop to organize cell division
What happens durning the G2 phase
- replishes ( refill) it’s okay mercy stores
- synthesizes protiens nessary for chromosome manipulation
- some cell organelles duplicate
- the cytoskeleton disintergrates to provide resources for mitotic phase
Mitosis is the division of _________cells
- somatic
What is karyokinesis
It’s the process in cell division where the nucleus divides
- prophase
- metaphase
- anaphase
- telophase
What is cytokinesis
the physical separation of the cytoplasmic components into the two daughter cells
What happens in the prophase
- nuclear envelope dissociates into small vesicles
- chromosomes become more condensed, discrete
and visible through compound microscope - sister chromatids coil more tightly to form kinetochore
- the kinetochore attracts and binds mitotic spindle microtubles
- organelle such as the golgi complex or Golgi apparatus and endoplasmic reticulum fragments disperse toward the periphery of the cell
What happens durning metaphase
- All the chromosomes are aligned at the metaphase plate or the equatorial plane
- The sister chromatids are still tightly attached to each other by cohesion proteins
What happens durning anaphase
-The sister chromatids are still tightly attached to each other by cohesion proteins
What happens durning telophase
- chromosomes begin to decondense (unravel)
- the mitotic spindles are depolymerized
- the nuclear envelopes form around the chromosomes
- nucleosides appear within the nuclear area
Meiosis is The division that produces
Sex cells (gametes )
Meiosis produces genetic variation through
A process of crossing over and independent assortment
Meiosis 1 is also called
Reduction division
What happens durning prophase 1
- nuclear envelope disintergrates
- chromosomes begin to condense
- spindle fiber appears
- non sister chromatids of homologous chromosome form chiasmata( the point where homologous chromosomes exchange genetic material)
What is a homologous chromosome
A diploid cell contains two copies of every chromosome, one derived from male gamete and the other from the female gamete. These pairs of chromosomes are called homologous chromosomes
What are sister chromatids
are the two chromatids of a replicated chromosome that are connected by the centromere
What are non sister chromatids
is one of the two chromatids of two homologous chromosomes
What happens durning prophase 2
- the chromosomes condense again into visible x shaped structures
DNA stores
Genetic information
What does mRNA do
It creates a complementary strand ( transcribes ) the DNA with the help of RNA polymerase
What does tRNA do
Brings an amino acid depending on the condon . The tRNA has complementary base pairs which are called anti condons
What does rRNA do
It makes up the ribosome
What are ribosomes
They are organelles that are found in the cytoplasm that translate mRNA into a protien . Basically they arrange the amino acids based on the mRNA
What is the central dogma
All processes of biological information flow
What is transcription
Is the process of making mRNA from DNA
A condon is a sequence of
Three nucleotides and four nitrogenous bases
What are stop condons and give examples
- stop the process of Protien synthesis
- UGA, UAA and UAG
What are intitator ( start ) condons
- initiates protien synthesis
- AUG
______ and _____ are also transcribed from DNA
- tRNA and rRNA
What happens durning transcription
- DNA separates
- mRNA is formed
- mRNA detaches from the DNA
- mRNA leaves the nucleus to go out into the cytoplasm and binds to ribosomes
What is translation
Is the process of protien syntheis from mRNA with the help of tRNA and rRNA
tRNA acts as an adapter that connects
The specific amino acid based on base complementarily
