Unit 4: Dna and Rna, Dna replication, Protein Synthesis, meiosis, Flashcards
what is dna and rna
they are nucleic acids, both made of nucleotides.
- sugar
- phosphate
- nitrogenous bases
what are the nitrogenous bases
adenine (a), thymine (t dna only), guaine (G), cytosine (c), Uracil (u rna only)
what does dba do
stores genetic information using its sequances of A, T, C, G
- this genetic information is the instructions to make an organisms proteins ( ex. like a recipe book for proteins)
what does dna stand for
deoxyribonucleic acid
what is the dna structure and what is it made out of.
What are the nitrogeneous bases for DNA
it has a double helix shape ( twisted ladder)
- deoxyribose sugar
- A,T,C,G
where is dna stored
the nucleous of eukaryotes
-what does Rna do
helps DNA make proteins
what are the 3 types of rna and what do they do
EACH ONE HAS ITS OWN JOB
- mRNA : carries DNA message as codons
- rRna: makes up ribosomes
- trna: matches anti-codon to mRna codon to bring the correct ameino acid
- what does rna stand for
- what is the structure of DNA
- Ribonucleic acid
- rna is single stranded
- made of ribose sugar
what are the nitrogenous bases for rna and where is it found
- A, U, C, G
- nucleus and cytoplasm
how do the nitrogenous bases connect
- held together by hydrogen bonds
In both: c-g
dna: a-t
rna- a-u
explain DNA replication
process of making a copy of DNA
- the DNA made during replication Is the exact same copy of the original DNA
- THIS HAPPENS IN S-PHASE OF INTERPHASE
explain semiconservative
each DNA molecule consists of an original strand and a new strand
what does dna require to replicate
it requires many enzymes ( proteins )
what does the following do:
- helicase
- DNA polymerase
- ligase
helicase - separates DNA strands
Dna polymerase- adds nucleotides + proofreads
ligase- links new pieces of dna
what is the central dogma
explains how life is determained threw DNA
DNA < RNA < proteins
what is a gene
a section of dna that codes for a protein is called a gene
- the gene is read, and the message is used to make a protein
what is photosynteisis
process of making proteins
2 steps: transcription and translation
what is trancscription
1) mRna copies dna instructions
what is translation
2) ribosomes use mRNA to make proteins
Transcription
location:
what is invloved:
what happens:
location: nucleous
what is invloved: dna + rna
what happens:
- DNA unwinds where gene is
- rna polymers use DNA as a template to ake an mRna copy
- now the mRna copy can leave the nucleus
what is a codon
sequance of 3 nucleotides that code for an ameino acid
- AUG is the start codon
Translation
- location
- what
- what happens
- ribosomes
- mrna, ribosome (mRna), Trna
- mRna finds a rubosome and binds to it, mrna codons are read by tRna.
- tRna brings in correct AA that matches codon. aneino acid links together to form protein
describe somatic cells
- Body cells
- found in body tissue + organs
- Dna in body cells arent passed to offspring
- ex. nerve cell
describe gamates
- sex cells
- eggs (female) sperm ( male)
-dna in gamates can be passed to an offspring
describe a chromosome
a condensed dna molecule with part (or all) of the genetic material of an organism
- humans have 23 pairs ( 46 in total)
there are 2 types of chromosomes: autosomes + sex chromosomes. describe them
autosome- chromosomes that carry traits
sex chromosome- chromosomes with genes related to biological sex
- XX = female
-XY= male
what are homologous chromosome
2 chromosomes with the same genes, but may have different versions of genes ( alles)
- 1 is from mother
-1 is from father
what is a Diploid
(2n) - these cells have 2 copies of each chromosome
- somatic cells
- have homologous chromosomes
what is a haploid
(n) think half- these cells have only 1 copy of each chromosome
- gamates
- don’t have homoglous chromosomes
what is fertilization
uniting of a sperm and and egg cell
- results in a diploid
- zygote = fertilized egg
mitosis
starts with one 2n cell + ends with two 2n cells
- somatic cells = more somatic cells
meiosis
starts with one 2n cell and ends with four 2n cells
- somatic cells= sex cells (gamates)
- meiosis produces 4 sex cells that are genetically different from one another and from original cell
- cells go through 2 rounds of division
- results in haploid cells
- reduceses chromosomes by half
- only happens in sex cells
Meiosis 1
seperates homologous chromosomes
( moms set seperates from dads set)
Interphase 1
- G1: cells grow and preform many of their required cellular functions
-S-phase: DNA us copied/ replicated - G2: makes proteins, grows
prophase 1
The nuclear envelope breaks down. The chromatin condenses into chromosomes.
- crossing over occurs
metaphase 1
- homologous chromosomes pairs are randomly lined up in middle of cell
- chromosomes are lined up along each side of cell equator
-independant assortment
anaphase 1
chromosomes are in pairs and are pulled away by spindle fibers
-sister chromotids remain toghther
teleophase 1
-nuclear membrane forms again (some species)
- spindle fibers dissasimble
- cell undergoes cytokenisis
END RESULT: two new haploid cells w duplicated chromosomes. 46 chromosomes
what are the two mechanisms that occur during meiosis 1
genetic diversity and variation
what is crossing over
- homologous pairs line up on opposite sides of equator, parts of chromotids and become twisted around each other
- this results in a new combination of alleles
what is independent assortment
- homologous pairs line up opposite sides of equator
- randomized
- pairs are separated, 1 of each homologous pair ends up in daughter cell
– creates large number of possible combinations of chromosomes in daughter cells produced
prophase 2
- nuclear membrane breaks down
-spindle fibers assemble
metaphase2
spindle fibers align chromosomes at cell equatpr
- each chromosome still has two sister chromotids
anaphase 2
-sister chromotids are pulled apart from each other by spindle fibers
