Inheritance 1 and 2 Flashcards
What does each duplicated chromosome consist of
Two identical chromosomes which are called Sister chromatids
What are sister chromatids are held together by
Centromere
How many chromosomes does a human cell contain
46, which form 23 pairs
What is a male sex chromosome
One x and one y
What is a female sex chromosome
2 x
Of the 46 chromosomes, how many are inherited from your parents
One of each pair (23) from your mum and the other 23 from your dad
What is DNA
A large molecule that contains genetic information
It is made up of a double helix structure made of two strands
What is the backbone of DNA made of
Alternating sugar (deoxyribose) and phosphate
What does the middle of DNA consist of
Bases-there are four Adrenaline (A) Thymine (t) Guanine (g) Cytosine (c)
What is a nucleotide
A unit of phosphate, sugar and a base
How did the bases always pair?
A always pairs with T
C always pairs with G
What is a gene
A small section of DNA/a chromosome that contains information for making protein
Each three bases contains the code for what
An amino acid
How many genes does eat chromosomes contain
Thousands
What are the proteins responsible for
Certain characteristics such as eyecolour
What is the first step of a cell dividing
- DNA double helix gets unwound
- And the two strands separate
What happens after the double helix has unwound when the cell is dividing
New DNA strands are made up by connecting free nucleotides together using the old strand as a template
The newly formed DNA double stands rewind into a double helix
What is the result of DNA replication
Newly Formed DNA molecules contain:
-one strand of the original DNA
-One new strand
This is called semiconservative replication
What is mitosis
The process of cell division
What is the order of mitosis
- Interphase
- Prophase
- Prometaphase
- Metaphase
- Anaphase
- Telophase
- Cytokinesis
What happens during interphase
- DNA is copied i.e. chromosomes are duplicated
- Chromosomes are not visible
What happens during prophase
- Chromosomes condense and become visible
- It’s chromosome consists of 2 chromatids
What happens during prometaphase
- The nuclear membrane disappears
- Spindle fibres are formed
What happens during metaphase
Spindle fibres align the chromosomes in the middle of the cell
What happens during anaphase
-Spindle fibres pull the chromatids apart to opposite ends of the cell
What happens during telophase
-A new nuclear membrane forms around each of the two sets of chromosomes
What happens during cytokinesis
-The cell starts to divide into two cells
What is the result of mitosis
- Two new daughter cells are forms
- They’re genetically identical to each other and to the parent cells (clones)
What are runners
Overground aerial stems which grow roots and development into new plants eg strawberries and spider plants
What are rhizomes
Underground stem is which grow through the soil, and will periodically produce new roots and new aboveground shoots eg grass
What are tubers
underground swollen stems from which new plants may grow eg. Potatoes
What are bulbs
Short stems with fleshy leaves e.g. onions/daffodils
Explain cuttings
- Remove a small part (stem or leaf) of the parent cell (= cutting)
- Plant cutting into soil, it will then grow into new plant
Explain micropropagation
- Take a few cells/or very small part of the plant (explants)
- Put them into culture medium (with nutrients and growth hormones)
- grow into a callous and from that the new plant to grow
How does micropropagation work
Plants contain many meristems cells which continuously divide by mitosis
Meristem cells are toti-potent and can differentiate into all kinds of plants tissues
Why clone plants
- To produce genetically identical copies of a plant does with desirable characteristics
- to quickly produce many mature plants
- To produce plants in the absence of pollinators
- To conserve rare or endangered plants
- To make copies of plants that have been genetically modified
What is the clone
Genetically identical copy of an organism or plant
What is a somatic cell
A cumulus cell. Cumulous cells are found in a layer of cells that surround and nourish egg cells
What happens during somatic cell nuclear transfer
First we have to remove the nucleus from the egg cell. We then remove the nucleus from the somatic cell and insert it to the egg cell . They then have to be left for a couple of hours while they are adjust to each other
What is a chromosome
A thread like structure made of DNA, found in the nucleus
What is a stem cell
A cell that can:
- Replicate themselves
- And differentiate into other cell types
What is a totipotent cell
A cell that can develop into any cells type
Zygote-Morula
Day1-day 5
What is a pluripotent cell
A cell that can develop into most cells types
-Blastula (one week)
Can develop into everything but placental cells and umbilical cord
What is a multipotent cell
A cell that can develop into some cell types
Fetus, baby, adult
What is a uni potent cell
Can develop into one cell type
What are the positives of using pluripotent stem cells / embryonic stem cells
- Can be isolated from early embryo and grown in a dish
- Promising source of cells for treating many diseases
- can become most cells
What are the negatives of using pluripotent stem cells/embryonic stem cells
- Body will recognise the cells as foreign and attack them so drugs for suppressing the immune system are needed
- there are ethical issues, destroys embryo…
- these don’t have the same genes as the person treated with them so might be rejected by patient
What are the positives of using multipotent stem cells
- Important for growth, healing and replacing cells that are lost through daily wear and tear
- used as a treatment for blood related diseases
- Therapy involving somatic stem cells is not controversial
- It can be isolated without causing harm to patients
- use of patience own cell as possible- no rejection
What are the negatives of multipotent stem cell uses
- Difficult to isolate and grow in culture
- Isolation of some types could cause considerable tissue or organ damage, as in the heart or brain
- immune system recognise transplanted cells as foreign and attacks them so drugs need to suppressed immune system
What is the purpose of meiosis
To make gametes - only occurs in ovaries and testes
How many cells are produced in meiosis
For
What happens to the chromosome number in meiosis
Halved (46-23)
In meiosis a parent daughter cells genetically identical
No
What is variation
Small differences between members of the same species.
There is genetic variation and environmental variation.
One is genes inherited by parents, the other is the influence of environment
What is genetic variation
Differences caused by genes inherited from parents
What is environmental variation
Differences caused by the environment
What does it homologous chromosome have the same of
Type of genes. E.g. eyecolour, earlobe shape…
What is an allele
A version of a gene
What is a dominant allele
Only one copy is necessary for characteristics to be shown
What is a recessive allele
Two recessive allele is a needed (no dominant allele present) for characteristics to be shown
What is a genotype
The genetic make up i.e. which alleles are present
What is a homozygous
Having two identical alleles
What is a heterozygous
Having two different alleles
What is a phenotype
The characteristics that is shown
What is a codominant
Both alleles contribute to the phenotype, so both characteristics are present at the same time
What is a pedigree tree
A family tree that records and traces the occurrence of a characteristic in the family
What is a mutation
Change in the order of bases in the DNA
What is a mutagen
An agent that causes mutation
What is a genetic disease
Condition or illness caused by mutations in genes or chromosomes
