dna & genetics study set

Where is DNA found?

condensed into chromosomes inside the nucleus of each cell (expect red blood cells)

What is the function of DNA?

dna makes up an organism’s genotype and determines how an organism looks and functions (phenotype)

dna holds genetic material and codes for protein which determines a trait

What does DNA look like?

like a twisted ladder

it is a double helix and has two strands

What is a gene?

a segment of dna that codes for a protein

What is a protein do?

determines a trait

they also are enzymes, building blocks, etc

What are alleles? How many alleles per gene?

alleles are different versions of a gene

2 per gene

What are chromosomes?

a package of dna or condensed dna

What are nucleotides? What are the components?

building blocks of DNA

made of phosphate group, deoxyribose sugar, and nitrogenous base

What are the complementary base pairing in DNA replication?

Adenine & Thymine

Cytosine and Guanine

Why is complementary base pairing important?

allows the 2 strands of dna to be the same

if they are not complementary then they can lead to mutations

Why is DNA double stranded?

so it can replicate and correct any mistakes

Define covalent and hydrogen bonds?

hydrogen bonds - weaker bonds, where the complementary bases meet

covalent bonds - stronger bonds, where the bases, phosphate, and sugar meet

What are the steps of DNA replication?

closed dna strand is unzipped by the helicase (enzyme/protein) and hydrogen bonds are broken

primed and prep strands for replication, then the first few nucleotides are added by primer

polymerase (enzyme/protein) pulls free floating nucleotides (around the nucleus) and builds up the new strand

Explain the function of each step in the DNA extraction lab

smush strawberry to separate cells from one another.

soap broke membrane and broke open nucleus revealing the DNA.

salt made the DNA clump together

alcohol separated the DNA from the strawberry because DNA is less dense so it floated and the strawberry sank

Where are chromosomes found?

inside the nucleus of every cell (except red blood cells)

How many chromosomes do we have?

46 chromosomes or 23 pairs

What are autosomes and how many do we have?

autosomes: any chromosome that is not a sex chromosome

22 pairs of chromosomes OR 44 chromosomes

What are sex chromosomes and how many do we have?

sex chromosomes

1 pair of chromosomes OR 2 chromosomes

females have two X chromosomes (XX)

males have one X and one Y chromosome (XY)

What are homologous chromosomes?

each chromosome and its partner are called homologous chromosomes. same gene in the same location. mirror image of each other.

contain alleles of same gene type

one homologous chromosome is inherited from the mother and one inherited from the father

What is a genome?

the complete set of genes or genetic material present in a cell or organism

all of the dna of an organism is called its genome

What is a gamete? Haploid or Diploid?

sex cells (haploid 23) (sperm and eggs)

What are zygotes? Haploid or Diploid?

combined sex cells (fertilized, diploid 46)

What does haploid mean?

a cell that contains a single set of chromosomes (23)

What does diploid mean?

a cell that contains a full set of chromosomes (46)

Explain the theory of blending inheritance

blending inheritance theory was that each parent contributes factors that blend in their offspring.

Explain Mendel theory

mendel’s findings from his experiments was that individual factors, which do not blend, control each trait of a living thing. 

Explain the effects of dominant and recessive alleles

the effects of a dominant allele are seen even if a recessive allele is present

the effects of a recessive allele are seen only if a dominant allele is not present

Explain homozygous (dominant / recessive)

when both alleles are the same

homozygous dominant (RR)

homozygous recessive (rr)

Explain heterozygous

when the alleles are different

one dominant and one recessive allele (Rr)

Explain genotype and phenotype

genotype consists of the alleles that the organism inherits from its parents (allele pp, Pp, PP)

phenotype of a PP or Pp or pp is the way it appears (purple, curly, etc)

What are punnet squares used for?

used to track alleles of each parent and predict the outcomes of crosses

What are pedigrees?

a family tree that tracks a particular trait through generations

Define complete dominance

when one allele is completely dominant over the other. 

example: heterozygous plants and dominant homozygous plants are indistinguishable in phenotype. Both plants PP and Pp for flower color have purple flowers

Define incomplete dominance

when two or more alleles influence the phenotype, resulting in a phenotype intermediate between the dominant trait and recessive trait. neither allele is completely dominant over the other allele. 

example: both allele for red flowers (R) and the allele for white flowers (r) influence the phenotype. When they self pollinate red-flowering plants produce only red-flowering offspring and white-flowering plants only produce white-flowering offspring. But when they are crossed, they will have pink flowers and 100% of the offspring would have pink flowers (Rr)

Define codominance

when both alleles for a gene are expressed in a heterozygous offspring (Pp). neither allele is dominant or recessive and they do not blend in the phenotype

example: the genes for both white coat (R’) and red coat (R) color are expressed. The color of the coat would be (RR’) and have both will be expressed

Define x-linked and y-linked genes

x-linked = genes found on x chromosomes

y-linked = genes found on y chromosomes

more genes can fit on the X chromosomes

x-linked genes affect men more because they only have one x chromosome

What is the significance of meiosis?

sexual reproduction

What is the significance of mitosis?

clone themselves to

• replace dying cells

• grow more so you need more

• reproduce

• protect tissue

• repair yourself

How many daughter cells are produced in mitosis?

2

How many daughter cells are produced in meiosis?

4

What is a monohybrid cross?

cross is between individuals that had one pair of contrasting traits

example: a cross between a plant that purely produces red flowers and a plant that purely produces green flowers

What is a dihybrid cross?

cross is between individuals with two contrasting traits

example: red flowers and yellow seeds: Green flowers and blue seeds

Which cells carry out meiosis?

germline cells

Which cells carry out mitosis?

somatic cells

When daughter cells are produced, are they identical to each other and the parent cell in mitosis and meiosis?

mitosis creates two identical daughter cells that each contain the same number of chromosomes as their parent cell (46)

meiosis creates four unique daughter cells, each of which has half the number of chromosomes as the parent cell (23)

Where does crossing over occur? Why?

occurs during meiosis

creates genetic variation between the chromosomes / different

Explain the significance of the fact that DNA is found in all living organisms

controls development, maintenance, and reproduction of all organisms

Explain how DNA replication contributes to creating diversity of life

ensures growth and renewal of large variety and diversity of new cell types

helps the inheritance process by transfer of genetic material from one generation to another

Explain how a mutation in DNA could affect the structure and function of a protein, and a trait

can bring about a change in the structure and function of the protein and lead to genetic disorders (ex. cancer)

Where are germline cells located?

ovaries and testies / produce the germline cells

When do females and males produce gametes?

females produce all egg cells before birth

males produce all sperm cells after birth

How many divisions are in meiosis and mitosis?

meiosis is 2 divisions

mitosis is 1 division

Where does crossing over occur in what process?

meiosis (not mitosis, no crossing over)